LIBRARY 

OF  THE 

UNIVERSITY  OF  CALIFORNIA. 


OIFT    OF 


PROF,  W,B,    RISING 

Class 


LABORATORY  EXERCISES 

WITH 

OUTLINES  FOR  THE  STUDY  OF 
CHEMISTRY 

TO  ACCOMPANY  ANY  ELEMENTARY  TEXT 


BY 


H.   H.  NICHOLSON 

Professor  of  Chemistry  in  the  University  of  Nebraska 


SAMUEL  AVERY 

Professor  of  Chemistry  in  the  University  of  Idaho 


NEW  YORK 

HENRY   HOLT  AND   COMPANY 

1899 


Copyright,  1899, 

BY 

HENRY    HOLT    &    CO. 


ROBERT   DRUMMOND,    PRINTER,    NEW  YORK 


PREFACE. 

THE  primary  object  of  the  authors  in  preparing  this 
book  is  to  place  in  the  hands  of  the  science  teachers 
in  the  State  a  laboratory  manual  adapted  to  the 
average  high-school  requirements.  In  it  we  have 
endeavored  to  emphasize  the  value  of  laboratory  in- 
struction in  the  laboratory. 

The  aim  is  to  give  the  student  facts,  practically  of 
his  own  finding,  before  a  discussion  and  correlation 
of  these  facts.  Our  experience  in  teaching  has  led  us 
to  the  conclusion  that  to  reach  the  best  results  a 
student  of  chemistry  must  first  be  given  experimental 
work.  In  this  way  his  interest  is  sufficiently  aroused 
to  hear  with  profit  descriptive  lectures,  or  to  read  with 
some  attention  the  discussion  of  facts  and  principles 
as  found  in  elementary  text-books.  To  this  end  he  is 
carefully  guided  in  his  experimental  work,  after  which 
he  is  expected  to  study  the  subject  of  his  experiment 
in  one  or  more  of  the  texts  referred  to  at  the  end  of 
each  exercise. 

These  texts  are  not  necessarily  the  best  that  might 
be  given,  but  they  are  in  many  cases  the  only  ones 
available  to  the  pupil.  They  are  in  all  cases  those 
found  to  be  at  hand  in  class  use  or  otherwise  in  the 
high  schools  of  this  State. 

In  all  cases  the  references  themselves  are  to  the 
specific  subject  under  investigation. 

It  is  not  intended  that  this  manual  should  take  the 

237442  in 


iv  PREFACE. 

place  of  any  of  the  many  excellent  text-books  now  in 
use,  but  rather  that  it  shall  supplement  and  make 
more  useful  those  now  in  the  hands  of  the  pupils  or 
in  the  school  libraries. 

The  authors'  acknowledgments  are  due  to  Mr. 
Jesse  E.  Beans  of  Omaha  for  his  efficient  service  in 
preparing  the  illustrations.  We  would  also  express 
our  thanks  to  Dr.  John  White  of  this  university  for 

valuable  suggestions. 

THE  AUTHOES. 
UNIVERSITY  OF  NEBRASKA, 
June  10th,  1899. 


ABBEEVIATIONS. 

THE   abbreviations   calling  for  explanation  are  as 
follows : 

cc.       cubic  centimeter.  grin.   gram. 

cm.      centimeter.  mm.    millimeter. 

Under  "  References  ": 

Clk.  Elements  of  Chemistry,  by  F.  W.  Clarke. 
New  York :  American  Book  Com- 
pany. Date  of  copyright  1884. 

Cly.  New  Text-book  of  Chemistry,  by  LeRoy 
C.  Cooley.  New  York :  American 
Book  Company.  Date  of  copyright 
1881. 

B.  (Briefer  Course.)  An  Introduction  to 

the  Study  of  Chemistry,  by  Ira 
Bemsen.  New  York :  Henry  Holt 
and  Company.  Date  of  copyright 
1893. 

S.  Elements  of  Inorganic  Chemistry,  by 

James  H.  Shepard.  Boston  :  D.  C. 
Heath  and  Company.  Date  of  copy- 
right 1885. 

S.  andL.  An  Elementary  Manual  of  Chemistry, 
by  F.  H.  Storer  and  W.  B  Lindsay. 


ABBREVIATIONS. 

New   York :    American    Book    Com- 
pany.    Date  of  copyright  1894. 
W.  Elements   of   Chemistry,   by   Rufus   P. 

Williams.     Boston :    Ginn   and  Com- 
pany.    Date  of  copyright  1897. 


SUGGESTIONS. 

A  NUMBER  of  carefully  selected  reference  books 
should  be  placed  in  the  school  library.  The  following 
are  especially  recommended : 

Inorganic    Chemistry    (Advanced   Course),    by   Ira 

Remsen.     Henry  Holt  and  Company,  New  York. 

General  Inorganic   Chemistry,    by  Paul  C.  Freer. 

Allyn  and  Bacon,  Boston. 
Organic  Chemistry,   by  Ira  Remsen.     D.  C.  Heath 

and  Company,  Boston. 

Treatise  on  Chemistry,  by  Koscoe  and  Schor- 
lemmer.  Volumes  I  and  II.  D.  Appleton  and 
Company,  New  York. 

The  articles  on  chemical  topics  in  the  "  Britannica " 
will  be  found  especially  valuable.  The  lives  of  famous 
investigators  may  be  studied  in  connection  with  their 
discoveries,  thus : 

In  connection  with  The  life  of 

Oxygen  < Priestley. 

Chlorine Scheele. 

Air Cavendish. 

Atomic  Weights Berzelius  and  Stas. 

Atomic  Theory  . . . .  , Dalton. 

Combustion Lavoisier. 

The  Alkali  Metals Davy. 

vii 


TO  THE  PUPIL. 

WOEK  independently.  You  are  not  concerned  with 
what  your  fellow  student  is  doing. 

Do  not  talk,  except  with  your  instructor  about  your 
work. 

Do  not  ask  questions  of  your  instructor  until  you 
have  tried  to  answer  your  questions  for  yourself. 

Keep  in  a  note-book,  especially  reserved  for  this 
use,  an  accurate  record  of  your  laboratory  work. 
Record  your  observations  when  you  make  them,  not 
from  memory  afterwards. 

Do  not  hurry. 

Keep  the  apparatus  clean. 

Work  cautiously,  using  small  quantities  of  re- 
agents ;  avoid  inhaling  poisonous  gases,  and  be  espe- 
cially careful  to  avoid  getting  acids,  alkalies,  or  any 
other  corrosive  or  poisonous  substance  into  the  eyes. 

viii 


CONTENTS. 


PAGE 

ABBREVIATIONS v 

SUGGESTIONS vii 

To  THE  PUPIL viii 

THE  NON-METALLIC  ELEMENTS. 

EXERCISE 

1.  Preliminary  Chemical  Manipulation 3 

2.  Physical  Changes  and  Chemical  Changes 7 

3.  Conditions  under  which  Chemical  Changes  take  place 9 

4.  Elements.     Mixtures  and  Compounds 11 

5.  Some  Chemical  Terms 13 

6.  Oxygen  :  Preparation  and  Physical  Properties 15 

7.  Chemical  Properties  of  Oxygen.     Problems 18 

8.  Hydrogen:  Usual  Method  of  Preparation  and  Characteristic 

Properties 21 

9.  Hydrogen — continued 24 

10.  Valence 27 

11.  Water 30 

12.  Chlorine 34 

13.  Hydrochloric  Acid 36 

14.  Classification  of  Certain  Compounds 39 

15    Nitrogen 42 

16.  Ammonia 44 

17.  NitricAcid 46 

18.  Compounds  of  Oxygen  and  Nitrogen 49 

19.  Carbon 52 

20.  Compounds  of  Carbon  and  Oxygen , .  55 

21.  Flames 58 

22.  Bromine 60 

23.  Iodine 63 

24.  Fluorine f 66 

25.  Sulphur 68 

26.  Sulphides 70 

27.  Sulphur  Compounds  containing  Oxygen , .  73 

ix 


VOATENT& 


EXERCISE  PAGE 

28.  Phosphorus 75 

29.  Arsenic 78 

30.  Silicon.    Boron.     Review  of  Non-metals 80 

THE  MORE  IMPORTANT  METALS. 

31.  The  Alkali  Metals 85 

82.  Compounds  of  the  Alkaline  Earths 88 

33.  Magnesium,  Zinc,  Cadmium,  and  Mercury 91 

34.  Copper,  Silver,  and  Gold 94 

35.  Aluminium 96 

36.  Tin  and  Lead 98 

37.  Chromium 100 

38.  Manganese... 102 

39.  Iron,  Cobalt,  Nickel,  and  Platinum 104 

SOME  FAMILIAR  HYDROCARBONS  AND  THEIR 
DERIVATIVES. 

40.  Some  Hydrocarbons 109 

41.  Some  Halogen  Derivatives  of  the  Hydrocarbons Ill 

42.  Alcohol 113 

43.  Some  Fatty  Acids 116 

44.  Some  Familiar  Carbohydrates 118 

45.  A  Few  Aromatic  or  Benzene  Derivatives 121 

APPENDIX. 

Information   for  Schools   needing  Equipment    for  Teaching 

Chemistry 125 


THE  NON-METALLIC  ELEMENTS. 


EXERCISE  1, 

PRELIMINARY  CHEMICAL  MANIPULATION. 

Select  a  sound  cork  and  a  sharp  borer.  Press  the 
small  end  of  the  cork  firmly  against  a  block  of  soft 
wood.  Place  the  borer  in  the  position  shown  in  Fig.  1, 
and  cut  a  hole  through  the  cork  by  twisting  the  borer 
back  and  forth,  applying  at  the  same  time  a  gentle 
downward  pressure. 

A  section  of  a  properly  bored  cork  will  appear  as  in 


FIG.  1. 


FIG.  3. 


Fig.  2  ;  when  the  hole  is  punched  instead  of  bored  the 
hole  will  appear  as  Fig.  3. 

A  hole  can  also  be  bored  to  advantage  as  follows : 
Proceed  as  just  directed  till  the  borer  has  cut  its  way 
about  half  through  the  cork,  then  remove  borer,  punch 
out  the  little  cylinder  of  cork  from  the  borer-tube,  and 
bore  from  the  other  end  of  the  cork.  A  little  practice 

3 


4:  THIS  NON-METALLIC  ELEMENTS. 

will  enable  you  to  strike  the  first  hole,  thus  forming  a 
single  boring  through  the  cork. 

To  fit  a  piece  of  glass  tube  into  a  cork,  proceed  as 
follows  :  Select  a  borer  a  trifle  smaller  than  the  tube 
that  you  wish  to  use.  If  no  borer  of  the  right  size  is 
at  your  disposal,  select  a  smaller  one  and  enlarge  the 
hole  with  a  round  file.  Now  insert,  by  pressure  and 
rotation,  a  tube  which  has  been  prepared  according  to 
directions  to  be  found  in  the  next  paragraph. 

Make  a  file-mark  on  a  piece  of  glass  tube  where  you 
wish  to  break  it  (a  few  inches  from  the  end).  Hold 
the  tube  as  shown  in  Fig.  4,  and  break  by  pulling  apart, 


FIG.  4. 

at  the  same  time  bending  slightly  downward.  The 
ends  of  the  tube  will  now  be  found  sharp,  and  must  be 
rounded  by  rotating  in  the  flame  of  a  burner.  Take 
care  in  rounding  to  heat  till  the  glass  just  softens,  and 
to  withdraw  from  flame  before  tube  begins  to  melt. 

For  practice  insert  three  tubes  into  a  cork  of  about 
2  inches  diameter,  as  shown  in  Fig.  5,  and  submit  to 
your  teacher  for  approval. 

Points  to  be  observed  :  (1)  The  tubes  must  fit  tightly. 
(2)  The  tubes  must  be  parallel. 

To  fit  a  cork  into  a  flask  (or  bottle),  proceed  as  fol- 
lows :  Select  a  cork  of  such  size  that  the  diameter,  at 
the  small  end,  is  just  a  little  smaller  than  the  mouth 


PRELIMINARY  CHEMICAL  MANIPULATION. 


of  the  flask.      Soften  the  cork  by  rolling  between  a 
piece  of  board  and  the  work-desk  as  shown  in  Fig.  6. 


FIG.  5. 


FIG.  6. 


Use  considerable  pressure  and  roll  for  about  a  minute 
(the  cork  may  be  placed  on  the  floor  and  rolled  with 
the  sole  of  the  shoe). 

For  bending  glass  tubing  the  ordinary  laboratory 
burner  will  not  answer.  The  best  results  are  obtained 
from  a  gas-burner.  If  the  laboratory  is  not  supplied 
with  gas,  use  an  ordinary  kerosene  lamp  without  the 
chimney  For  practice,  hold  a  piece  of  fairly  thick- 
walled  tube  of  3  to  5  mm.  in  diameter  outside  measure 
(j.  to  T3^  inch)  in  the  position  shown  in  Fig.  7,  Rotate 


FIG.  7. 


FIG.  8. 


FIG.  9. 


the  tube,  and  when  sufficiently  hot  bend  to  the  desired 
angle.  Now  bend  a  tube  as  shown  in  Fig.  8,  and  show 
to  your  teacher  for  approval. 


6 


THE  NON-METALLIC  ELEMENTS. 


Points  to  be  observed  :  (1)  There  must  be  no  marked 
contraction  at  the  bend.  (2)  The  arms  must  be  in  the 
same  plane  and  at  right  angles. 

Fig.  9  represents  a  piece  of  tube  bent  in  a  Bunsen 
or  alcohol  burner. 

It  is  often  necessary  to  draw  out  glass  tubing  to  a 
smaller  bore.  For  this  purpose  the  tube  is  rotated 

in  the  flame  of  the  burner 
till  the  glass  softens.  Now 
remove  from  the  flame  and 
pull  the  tube  to  the  desired 
bore. 

When  you  can  successfully 
follow  directions  up  to  this 
point  set  up  a  wash-bottle  as 
shown  in  Fig.  10. 

Use  a  500-cc.  flask  and  3  to 
5  mm.  diam.  glass  tube.  The 
wash-bottle  is  to  be  filled 
with  distilled  water  and  re- 
served for  future  use. 
L.,  pp.  395-398  and  406-497 ; 


FIG.  10. 


References :    S. 
W.,  pp.  384-388. 


and 


EXERCISE  2. 

PHYSICAL  CHANGES  AND  CHEMICAL  CHANGES. 

EXPLANATION  :  Physical  changes  do  not  affect  the 
composition  of  substances.  Chemical  changes  result 
in  the  formation  of  new  substances. 

In  the  following  experiments,  («)-(/),  show  when 
chemical  and  when  physical  changes  take  place. 

(a)  Hold  by  means  of  the  tongs  a  piece  of  platinum 
wire  in  the  flame  till  it  glows.  Cool  and  examine. 

(&)  Try  to  repeat  the  same  experiment,  using  mag- 
nesium ribbon  instead  of  the  platinum  wire. 

(c)  Put  a  piece  of  tin  (J  grm.)  into  a  test-tube  and 
heat  till  the  glass  begins  to  be  red.     Cool  and  examine. 

(d)  Heat  a  little  sugar  in  the  same  way. 

(e)  Procure  a  piece  of  Iceland  spar,  weighing  about 
1  grm.     Note  its  appearance  and  form,  especially  the 
angles.     Is  it  soluble  in  water  ?     Now  lay  the  piece  on 
the  bottom  of  an  inverted  mortar  and  strike  with  the 
pestle,  breaking  the  piece  into  fragments.     Examine 
the  fragments  with  a  hand-lens,  noting  the  form  as 
before. 

(/)  Put  the  fragments  obtained  in  the  last  experi- 
ment into  an  evaporating-dish  and  add  a  few  drops  of 
dilute  hydrochloric  acid.  Warming  hastens  the  re- 
action. When  action  ceases  add  a  few  more  drops  of 
acid,  repeating  the  process  till  a  further  addition  of  a 
drop  of  the  acid  produces  no  effect.  The  spar  should 
be  entirely  dissolved.  Now  place  the  evaporating-dish 

7 


8  THE  NON-METALLIC  ELEMENTS. 

on  a  wire  gauze  supported  by  the  ring-stand,  and  heat 
cautiously  till  all  of  the  liquid  is  driven  off.  The 
evaporation  should  be  carried  out  under  the  hood,  or 
where  the  draft  is  good.  Examine  the  residue.  Is  it 
Iceland  spar  ?  Is  it  soluble  in  water  ? 

References :  Clk.,  pp.  1,  2  ;  Cly.,  pp.  1-3  ;  R,  pp.  1-3 ; 
S.  and  L.,  pp.  7,  8  ;  W.,  pp.  1,  2. 


EXERCISE  3. 

CONDITIONS  UNDER  WHICH  CHEMICAL  CHANGES  TAKE 
PLACE. 

In  this  exercise  point  out  the  conditions — as  heat- 
ing, bringing  into  contact,  submitting  to  the  action 
of  the  light,  dissolving,  etc. — under  which  chemical 
changes  are  produced. 

(a)  Heat  a  little  potassium  chlorate  (J  grm.)  in  a 
dry  test-tube,  and  when  the  molten  substance  seems 
to  boil,  insert  a  glowing — not  a  flaming — splinter  of 
wood  into  the  test-tube. 

(b)  Place  a  little  tin  (1  grm.)  in  a  beaker  and  add 
1  cc.  concentrated  nitric  acid. 

(c)  Place  in  the  mortar  a  crystal  of  potassium  chlo- 
rate as  large  as  a  grain  of  wheat,  and  in  contact  with 
it  an  equal  amount  of  sulphur.    Now  protect  the  hand 
with  a  towel  or  glove,  and  grind  the  two  substances 
vigorously  together. 

(d)  Procure  from  your  teacher  a  piece  of   "  blue- 
print "  paper  (about  1  by  2  inches)  that  has  not  been 
exposed  to  strong  light.     Divide  it    into  halves   and 
place  one  in  the  direct  sunlight  for  fifteen  minutes.    If 
the  day  is  dark,  leave  it  exposed  in  the  window  till 
your  next  period  ;  the  other  half  is  to  be  kept  in  the 
dark  (between  the  leaves  of  a  book).     After  the  one 
piece  has  been  sufficiently  exposed  t'o  the  light,  put 
both  pieces  in  water  to  dissolve  out  any  unchanged 
coloring  matter.    Compare  the  color  of  the  two  pieces. 

9 


10  THE  NON-METALLIC  ELEMENTS. 

(e)  Grind  together  in  a  mortar  equal  quantities 
(J  grin,  each)  of  sodium  bicarbonate  and  tartaric  acid. 
Does  any  change  take  place  ?  Now  place  the  mixture 
in  a  test-tube  and  add  a  little  water.  What  do  you 
observe  ? 

(/)  Describe  the  application  of  electricity  in  pro- 
ducing chemical  change.  Refer  to  your  text-book  for 
the  answer  to  this  question. 

References  :  Clk.,  pp.  5,  6,  36,  37  ;  Cly.,  pp.  4-7  ;  E.? 
pp.  4-7. 


EXERCISE  4. 

ELEMENTS,  MIXTURES,  AND  COMPOUNDS. 

In  this  exercise  roll  sulphur,  not  flowers  of  sulphur,  must  be  used. 
The  iron  should  be  "iron  reduced  by  hydrogen."  Do  not  use  iron 
filings. 

(a)  Take  a  few  pieces  of  roll  sulphur  and  carefully 
study  its  physical  properties.     Hold  a  fragment  on  a 
piece  of  wire  in  the  flame  of  the  burner  and  note  the 
color  of  the  sulphur  flame,  and  the  odor  given  off. 
Now  powder  the  pieces  in  a  mortar.     How  can  you 
show  that  the  powdered  substance  is  still  sulphur  ? 

(b)  Put  a  little  of  the  powdered  sulphur  into  a  dry 
test-tube  and  add  to  it  2  or  3  cc.  of  carbon  disulphide. 
(Caution  :  Keep  carbon  disulphide  away  from  flames, 
as  it  is  very  inflammable.)     What  becomes  of  the  sul- 
phur in  the  test-tube  ?     Pour  the  liquid  in  the  tube 
into    a  watch-glass   and   let   stand   for  a  short  time. 
What  takes  place?     Explain  these  phenomena. 

(c)  Treat  a  little  (J  grm.)  iron  with  carbon  disul- 
phide just  as  you  did  the  sulphur.     Is  the  iron  solu- 
ble? 

Note.— Do  not  be  confused  in  your  conclusions  by  traces  of  iron 
that  may  be  held  in  suspension,  or  by  traces  of  sulphur  that  com- 
mercial carbon  disulphide  often  holds  in  solution. 

Dust  a  little  iron  into  the  flame  of  the  burner.  What 
do  you  notice?  Is  iron  attracted  by  the  magnet? 
State  all  the  points  of  difference  that  you  have  ob- 
served between  iron  and  sulphur. 

You  have  now  studied  some  of  the  properties  of  two 
elements.  What  is  an  element?  See  text  (index). 

11 


12  TEE  NON-METALLIC  ELEMENTS. 

(d)  Grind  together  in  a  mortar  3  grms.  of  sulphur 
with  5  grms.  of  the  powdered  iron.     Does  any  change 
take  place  ?  Examine  carefully  with  a  magnifying-glass. 
Can  you  see  the  iron  or  the  sulphur?     Spread  out  on 
a  sheet  of  paper  a  small  portion  and  see  if  you  can 
separate  the  iron  from  the  sulphur  by  passing  the 
magnet  just  above,  not  quite  touching  the  thin  layer 
on  the  paper.    Can  you  separate  the  iron  from  the  sul- 
phur by  physical  means  ? 

(e)  Take  another  portion  of  the  material  prepared 
in  (d)  and  treat  with  carbon  disulphide  in  a  test-tube. 
Put  your  thumb  over  the  top  of  the  tube  and  shake 
the  contents  of  the  tube  thoroughly,  cork  the  tube  and 
let  it  stand  quietly  for  a  few  minutes,  then  pour  off 
the  liquid  into  a  watch-glass,  being  careful  not  to  dis- 
turb the  solid  in  the   bottom.     Let  the  watch-glass 
stand  until  the  liquid  has  evaporated.    What  remains? 
How  do  you  know  ?     What  remains  in  the  test-tube  ? 
How  do  you  recognize  it  ? 

(/)  What  have  you  accomplished  in  this  experi- 
ment? Take  the  rest  of  the  material  prepared  in  (d) 
and  put  it  in  a  dry  test-tube  ;  heat  strongly  in  a  lamp- 
flame>  What  takes  place  ?  Break  the  tube  and  pul- 
verize its  contents  in  a  mortar  ;  compare  it  with  the 
substances  used  in  experiments  (c),  (d),  and  (e).  Have 
you  now  a  chemical  compound  ?  Why  do  you  think  so  ? 

Write  a  resume  of  (a)  to  (/)  inclusive,  telling  what 
classes  of  substances  have  been  used ;  what  facts 
have  been  observed  and  your  explanation  of  these 
facts. 

References:  Clk.,  pp.  8,  9  to  Table  1 ;  Cly.,  pp.  8,  9 
to  exercises ;  E.,  pp.  10,  12 ;  S.,  pp.  8,  11 ;  S.  and  L., 
pp.  9,  10 ;  W.,  pp.  5,  6  to  Sec.  8. 


EXERCISE  5. 

SOME  CHEMICAL  TERMS. 

This  exercise  contains  no  laboratory  work.  It  is  intended  to  review 
the  preceding  exercises,  and  to  familiarize  the  student  with  certain 
chemical  expressions  that  occur  in  the  exercises  that  follow.  The 
knowledge  necessary  to  answer  the  questions  may  be  derived  from 
previous  study,  from  explanations  from  the  teacher,  and  from  any 
work  on  chemistry  in  the  school  library. 

Name  five  instances  of  physical  change  and  as  many 
instances  of  chemical  change  that  you  have  noticed 
outside  of  the  laboratory. 

Can  the  same  force  under  different  conditions  pro- 
duce both  physical  changes  and  chemical  changes  ? 

Can  a  chemical  change  (as  the  burning  of  oil  in  the 
lamp)  produce  a  physical  change  ? 

What  do  you  understand  by  the  terms:  element; 
compound;  mixture? 

What  is  meant  by  the  terms  :  atom ;  atomic  weight; 
molecule;  molecular  weight? 

Explain  in  ordinary  language  the  expression  : 

Fe  +  S  =  FeS. 

If  the  relative  weights  of  the  atoms  of  iron  and  sul- 
phur are  as  56  :  32,  how  much  of  each  will  you  have  to 
take  to  form  eighty-eight  pounds  of  iron  sulphide? 
eighty-eight  grams  ?  eighty-eight  tons  ? 

The  weight  relations  expressed  in  the  problem 
depend  on  the  law  of  the  "  Indestructibility  of  Mat- 
ter." State  this  law.  What  is  a  natural  law? 

13 


i.4  THE  NON-METALLIC  ELEMENTS. 

References  (in  addition  to  those  given  in  Exercises  2, 
3,  and  4):  Oik.,  pp.  10-13;  Cly.,  pp.  10-15,  17-19;  K, 
pp.  16-19,  71,  76-82 ;  S.,  pp.  14r-19 ;  S.  and  L.,  pp. 
26,27;  W.,  pp.  16-18. 


EXERCISE  6. 

OXYGEN  :  PREPARATION  AND  PHYSICAL  PROPERTIES. 

Preliminary  Experiment. — To  collect  a  gas  not  soluble 
in  water  proceed  as  follows :  Pour  water  into  a  pneu- 
matic trough  till  the  water  rises  above  the  shelf.  Fill 
a  bottle  with  water  and  cover  with  a  piece  of  writing- 
paper,  taking  care  to  exclude  all  air-bubbles.  Now, 
pressing  the  paper  against  the  mouth  of  the  bottle 
with  the  fingers,  place  the  bottle,  mouth  downward,  in 
the  trough  and  withdraw  the  paper  below  the  surface 
of  the  water.  Set  the  bottle— entirely  full  of  water — 
on  the  shelf  of  the  pneumatic  trough.  (See  position 
of  large  test-tube  in  Fig.  11.)  A  tube  is  used  to  con- 
duct the  gas  ink  the  bottle.  Fill  the  bottle  with  ex- 
haled breath  by  blowing  through  a  tube. 

Oxygen  may  be  collected  most  conveniently  by  dis- 
placement of  water. 

To  prepare  oxygen  set  up  apparatus  as  shown  in 
Fig.  11.  Place  in  the  small  test-tube  a  mixture  of 
equal  weights  of  potassium  chlorate  and  manganese 
dioxide  (2  grms.  each  ground  together  in  a  mortar), 
and  heat  gently  at  first,  gradually  increasing  the  tem- 
perature till  the  gas  comes  off  freely.  When  this  stage 
is  reached  conduct  the  heating  in  such  a  way  as  to 
secure  a  gradual  evolution  of  gas.  Hold  the  burner 
in  the  hand  and  heat  all  parts  of  the  mixture  equally. 

Collect  two  or  three  bottles  of  oxygen.  When  oxy- 
gen ceases  to  come  off  or  when  your  bottles  are  full 

15 


16 


THE  NON-METALLIC  ELEMENTS. 


remove  the  delivery-tube  at  once  from  the  test-tube 
to  prevent  the  water  from  drawing  back  into  the  test- 
tube. 

Made  in  this  way  oxygen  looks  cloudy  on  account 


of  impurities.  These  will  nearly  all  dissolve  out  by 
allowing  the  bottles  to  stand  for  fifteen  minutes  in  the 
trough.  (Employ  this  time  in  writing  up  your  notes 
and  in  making  a  drawing  of  the  apparatus  used.) 

Now  place  a  piece  of  glass  plate  or  pasteboard  be- 
low the  surface  of  the  water  under  the  mouth  of  one 
of  the  bottles  and  invert  it.  Insert  a  splinter  with  a 
spark  on  the  end.  What  takes  place  ?  This  is  a  test 
for  oxygen. 

Try  to  determine  whether  oxygen  is  heavier  or 
lighter  than  air  in  the  following  way  :  A  bottle  with 
its  mouth  downward,  closed  with  a  glass  plate,  is  sud- 
denly opened  and  at  the  same  time  a  glowing  splinter 
is  brought  up  into  the  mouth  of  the  bottle  from  below. 


OXYGEN— PHYSICAL  PROPERTIES.  17 

Another  bottle  with  the  mouth  upward  is  uncovered 
and  a  glowing  splinter  inserted  from  above.  Does  the 
oxygen  seem  to  fall  to  meet  the  spark  or  does  it  rise  ? 
Is  the  difference  at  all  striking? 

Has  oxygen  any  odor,  color,  or  taste  ? 

Oxygen  may  also  be  prepared  by  other  methods,  as 
follows : 

(a)  Heat  a  little  potassium  chlorate  and  test  as  in 
section  (a)  of  Exercise  3.     Does  this  or  the  method 
last  used  seem  to  require  the  higher  temperature  ? 

(b)  Heat  a  little  chromic  acid  in  a  test-tube  and  test 
the  escaping  gas  for  oxygen. 

(c)  Prepare  oxygen  by  heating  mercuric  oxide  in  the 
following  way :    An  ignition-tube  containing  a  little  of 
the  oxide  is  attached,  by  means  of  a  short  piece  of 
rubber  tube,  to  a  delivery-tube.      The  oxide  is  now 
heated  very  gradually  at  first  to  avoid  cracking  the 
glass,  afterwards  to  a  high  temperature.     After  the 
escape  of  a  few  bubbles  (consisting  of  air)  the  oxygen 
evolved  is  collected  by  displacement  of  water.     Col- 
lect in  a  test-tube  and  prove  that  you  have  obtained 
oxygen. 

Note. — Small  ignition-tubes  may  be  made  as  follows:  A  piece  of 
tubing  long  enough  for  two  ignition-tubes  is  rotated  in  the  flame 
till  the  heat  gradually  separates  the  tube  into  two  parts  of  equal 
length.  The  hot  parts  are  protected  from  too-rapid  cooling  by  cover- 
ing with  soot  from  the  luminous  flame  of  a  gas-burner.  (A  kerosene 
lamp  with  the  chimney  removed  may  be  used  instead  of  the  gas 
burner. 


EXERCISE  7. 
CHEMICAL  PROPERTIES  OF  OXYGEN.    PROBLEMS. 

In  testing  the  action  of  gases  care  should  be  taken  to  prevent  un- 
necessary diffusion  ;  hence  the  bottles  should  be  kept  well  covered 
and  the  substances  used  in  the  tests  should  be  introduced  through 
small  openings.  Solids  may  be  conveniently  introduced  by  means  of 
a  deflagrating- spoon.  Such  a  spoon  may  be  made  of  crayon  and  wire 
as  shown  in  Fig.  12. 

Oxygen  unites  with  every  other  element  except  fluo- 
rine ;  hence  it  possesses  great  chemical  activity.  Is  it 
chemically  active  with  most  substances  at 
ordinary  temperatures?  To  determine  this 
introduce  into  a  bottle  of  the  gas  a  small 
piece  of  charcoal,  and  allow  it  to  remain 
several  minutes.  Do  you  notice  any  change  ? 
Why?  Eepeat  the  same  process,  using  a 
small  piece  of  sulphur.  What  is  the  result? 
What  do  these  experiments  show  ?  Now  set 
•IG  fire  to  a  piece  of  charcoal  and  allow  it  to 
remain  in  the  air  for  a  few  minutes  ;  then  insert 
it  into  a  jar  of  oxygen.  Is  there  any  difference 
in  the  manner  in  which  it  burns?  What  causes 
this  difference  ?  Repeat  the  process,  using  sulphur. 
What  do  you  observe?  Are  the  products  of  com- 
bustion the  same  when  substances  burn  in  air  as 
when  they  burn  in  pure  oxygen  ?  Give  reasons  for 
your  answer.  Heat  the  end  of  a  picture-wire  and  dip 
into  flowers  of  sulphur.  Set  fire  to  the  sulphur  ad- 
hering to  the  wire  and  insert  into  a  bottle  containing 

18 


OXYGEN—  CHEMICAL  PROPEETIES.  19 

oxygen.  Describe  what  takes  place.  What  is  the 
nature  of  the  substance  formed  ?  Does  the  amount  of 
oxygen  that  can  be  procured  from  1  grm.  of  potassium 
chlorate  ever  vary  ? 

Does  a  given  amount  of  mercuric  oxide  always  yield 
a  definite  amount  of  oxygen  ? 

What  do  you  understand  by  the  "  law  of  definite 
proportions  "  ?  Explain  the  meaning  of  the  expres- 
sions : 

KC1O3  =  KC1  +  3O. 
HgO  =  Hg  +0. 
2CrO,  =  CraO,  +  3O. 

(1)  How  much  oxygen  can  you  get  from  1  grm.  of 
mercuric  oxide  ? 

Calculation  :  From  the  text-book  you  find  that 
oxjTgen  and  mercury  have  atomic  weights  of  16  and 
200  respectively  ;  hence  mercuric  oxide  has  a  molecu- 
lar weight  of  216. 

HgO  =  Hg  +  O  ; 
216    =  200  +  16  ; 

hence     —  ^r^  —  =  7.41$  oxygen  in  mercuric  oxide. 


of  1  grm.  —  0.0741  grm.  of  oxygen. 
Second  calculation  : 

Molecular  Weight.    Atomic  Weight.    Weight  in  grms.  Weight  in  grms. 

HgO       :        O  =  Mercuric  oxide  :  oxygen  sought. 
216        :       16  =  1          :  '  x. 

x  =  =  0.0741  —  grm.  oxygen. 


20  THE  NON-METALLIC  ELEMENTS. 

(2)  How  much  mercury  would  be  liberated  in  maL 
ing  1  grm.  of  oxygen  ? 

(3)  How  much  mercuric  oxide  would  you  have  to 
take  to  obtain  1  grm.  of  oxygen  ? 

Solve  the  three  following  by  the  formula : 

KC1OS  =  KC1  +  30. 
122.5     =  74.5  +  48. 

(4)  How  much  oxygen  can  you  get  from  1  grm.  of 
potassium  chlorate  ? 

(5)  How  much  potassium  chloride  (KC1)  would  be 
left  after  driving  off  all  the  oxygen  from  1  grm.  of  po- 
tassium chlorate  ? 

(6)  How  much  potassium  chlorate  will  you  have  to 
decompose  in  order  to  get  1  grm.  of  oxygen  ? 

References  :  Oik.,  pp.  24-31,  72-75  ;  Cly.,  pp.  83-87; 
E.,  pp.  20-36,  83-87 ;  S.,  pp.  23-32 ;  S.  and  L.,  pp. 
15-18  ;  W.,  pp,  19-25. 


EXERCISE  8. 

HYDROGEN  :   USUAL  METHOD  OF  PREPARATION  AND  CHAR- 
ACTERISTIC PROPERTIES. 

Fit  a  wide-mouthed  bottle  with  a  good  cork,  through 
which  is  passed  a  thistle-tube  and  a  delivery-tube. 
See  larger  bottle  in  Fig.  13  (the  smaller  bottle  is  not 
used  in  the  first  part  of  this  exercise).  Hydrogen  is 
the  lightest  substance  known,  hence  it  can  readily  pass 
through  parts  of  apparatus  that  are  sufficiently  tight 
to  contain  other  gases.  The  cork  must  be  well  rolled 
and  pressed  very  tightly  into  the  neck  of  the  bottle. 
Rubber  connections  may  be  bound  with  a  cord  or  with 
fine  wire. 

Put  about  twenty-five  grms.  of  granulated  or  sheet 
zinc  into  the  bottle  ;  replace  the  cork  and  tubes,  tak- 
ing care  that  the  thistle-tube  extends  to  within  about 
two  mm.  of  the  bottom  of  the  bottle.  Pour  through 
the  thistle-tube  dilute  sulphuric  acid,  a  few  cc.  at  a 
time  in  order  that  the  evolution  of  gas  may  not  be  too 
rapid.  In  case  hydrogen  is  not  at  once  generated 
freely,  add  a  little  copper  sulphate  solution  through 
the  thistle-tube.  "When  you  think  that  all  air  has  been 
expelled  from  the  apparatus  collect  several  bottles  of 
the  gas  by  displacement  of  water  for  use  in  the  follow- 
ing experiments  : 

(a)  Thrust  a  glowing  splinter  upward  into  a  bottle 
of  hydrogen.  Does  hydrogen  burn  at  the  mouth  ot 
the  bottle  ?  Does  it  support  combustion  ? 

21 


22  THE  NON-METALLIC  ELEMENTS. 

(b)  Allow  a  bottle  to  stand  uncovered  for  one  to  two 
minutes.     Does  it  now  contain  hydrogen  ?    (Test  with 
spark.)     Repeat   the   experiment   holding   the  bottle 
with  its  mouth  downward.     Does  it  now  contain  hy- 
drogen ? 

(c)  Try  to  pour  hydrogen  up  into  a  bottle  in  the  fol- 
lowing way:    A  bottle  of  hydrogen  with  its  mouth 
downward  (closed)  is  held  beside  a  bottle  containing 
air.     Remove  the  plate  from  the  mouth  of  the  bottle 
containing  hydrogen  and  pour  the   gas  up  into  the 
other  bottle.     Does  this  bottle  now  contain  hydrogen 
(or  a  mixture  of  hydrogen  and  air)  ? 

If,  now,  the  greater  part  of  the  zinc  has  dissolved, 
empty  out  the  contents  of  the  generator  and  recharge. 
When  all  air  is  expelled  fill  a  toy  balloon.  Does  the 
balloon  rise  ?  Why  ?  Allow  the  balloon  to  rise  to 
the  ceiling.  Does  it  fall  after  a  time  ?  Why  ? 

What  do  you  conclude  from  these  experiments  con- 
cerning the  lightness  of  hydrogen  ? 

Made  in  this  way  hydrogen  has  an  odor  due  to  im- 
purities. Remove  these  by  passing  the  gas  through  a 
solution  of  potassium  permanganate  (one  part  to  thirty 
parts  of  water).  See  Fig.  13. 

Collect  a  bottle  of  the  pure  gas  and  notice  whether 
it  has  any  odor,  color,  or  taste. 

Fill  a  bottle  one  third  full  of  water,  close  tightly 
with  the  hand  and  place  mouth  downward  on  the  shelf 
of  the  pneumatic  trough ;  the  bottle  is  now  two  thirds 
full  of  air.  Fill  the  remaining  one  third  with  hydro- 
gen by  displacement  of  the  water  in  the  bottle.  Re- 
move the  bottle  and  apply  a  lighted  splinter,  keeping 
the  bottle  well  closed  till  the  instant  of  ignition.  This 
experiment  shows  the  explosive  character  of  a  mixture 
of  hydrogen  and  air.  Before  lighting  a  jet  of  hydro- 


HYDROGEN:   CHARACTERISTIC  PROPERTIES. 


23 


gen  always  collect  a  large  test-tube  of  the  gas  by  dis- 
placement of  water  and  apply  a  flame  at  the  instant  of 
uncovering.  If  only  a  slight  puff  occurs  and  the  gas 


FIG.  13. 

burns  quietly,  you  can  safely  light  the  hydrogen  as  it 
issues  from  the  generator.  Always  make  this  test  to 
avoid  dangerous  explosions.  Now  remove  the  bottle 
containing  the  permanganate  solution  and  connect  a 
blowpipe  with  the  delivery-tube  of  the  generator  at  A 
(Fig.  13).  Light  the  hydrogen  as  it  issues  from  the 
opening  in  the  end  of  the  blowpipe.  What  is  the 
character  of  the  flame  ?  Does  it  emit  much  light  or 
much  heat? 

Fill  a  beaker  with  water  to  keep  the  surface  cool 
and  hold  over  the  flame.  What  collects  on  the  cool 
glass  ?  What  is  formed  when  hydrogen  burns  ? 

Eeserve  the  zinc  solution  in  the  generator  for  study 
in  the  next  exercise. 


EXERCISE  9. 

HYDROGEN— CONTINUED. 

The  bottle  used  in  generating  hydrogen  in  the  last 
exercise  contains,  besides  undissolved  zinc  and  im- 
purities, zinc  sulphate,  either  in  solution  or  in  the 
form  of  a  crystalline  solid.  If  in  solution,  filter  and 
evaporate  the  clear  filtrate  on  the  water-bath  to  such 
a  degree  of  concentration  that  crystals  will  gradually 
separate  out  on  cooling  (try  two  thirds  former  volume). 
If,  on  the  other  hand,  you  find  crystals  in  the  bottle, 
dissolve  them  by  heating  the 
bottle  and  its  contents  in  the 
water-bath.  Filter  and  without 
concentration  set  aside  to  crystal- 
lize. 

The  crystals  consist  of  zinc  sul- 
phate crystallized  with  seven 
molecules  of  water.  Show  them 
to  the  instructor.  (Note  on  fil- 
tration.— A  -  circular  filter-paper 
is  folded  into  halves,  then  quar- 
ters. It  is  now  opened  out  into 
a  cone  having  an  angle  of  60°. 
Place  it  in  a  funnel  and  wet  with 
The  paper  should  fit  the  funnel 


FIG.  14 


distilled   water, 
closely.) 

Filtration  is  more   rapid  when  a   folded  filter,  as 
shown  in  Fig.  14,  is  used. 

24 


HYDROGEN—  CONTINUED.  2  5 

Explain  the  meaning  of  the  reaction  : 

Zn  +  H2S04  =  ZnSO4  +  Ha. 
65+98       =     161     +  2. 

Solve  the  following  problems  according  to  the  above 
reaction : 

(1)  How  much  hydrogen  can  you   get  using   100 
grms.  zinc  ? 

(2)  How  much  sulphuric  acid  is  required  to  dissolve 
100  grms.  zinc  ? 

(3)  How  much  zinc  and  how  much  sulphuric  acid 
will  you  require  to  produce  a  gram  of  hydrogen  ? 

A  liter  (approximately  a  quart)  of  hydrogen  weighs 
.0896  grm. 

(4)  How  many  liters  of  hydrogen  will  be  produced 
in  problem  3  ? 

(5)  How  much  zinc  and  how  much  sulphuric  acid 
would  be  required  to  produce  a  liter  of  hydrogen  ? 

Hydrogen  can  also  be  prepared  by  other  methods. 
(Perform  experiments  (a)-(d)  in  a  test-tube  and  test 
the  escaping  gas  with  a  flame.) 

(a)  Treat  a  little  zinc  with  hydrochloric  acid. 

(6)  Treat  a  little  iron  with  dilute  sulphuric  acid. 

(c)  Perform  the  same  experiment  using  hydrochloric 
instead  of  sulphuric  acid. 

(d)  Treat  aluminium  (£  grm.)  with  dilute  sodium 
hydrate  solution  and  warm. 

(e)  Heat  in  a  beaker  a  little  water  almost  to  boiling. 
Now  drop  in  a  piece  of  sodium  as  large  as   a  grain  of 
barley,  and  cover  the  beaker  with  a  glass  plate.    "What 
takes  place  ?   Test  the  solution  with  red  litmus  paper. 
Does  it  react  the  same  as  the  sodium  hydrate  on  your 


V6  TEE  NON-METALLIC  ELEMENTS. 

desk  ?     Consult  your  text  for  symbols  and  write  the 
reaction  between  sodium  and  water. 

References :  Clk.,  pp.  14-23  ;  Cly.,  pp.  60-69  ;  B., 
pp.  37-46  ;  S.,  pp.  34-48 ;  S.  and  L.,  pp.  34-43 ;  W., 
pp.  31-38. 


EXERCISE  10. 
VALENCE. 

You  have  already  learned  (Exercise  5)  that  the 
hydrogen  atom  is  taken  as  the  unit  in  which  atomic 
and  molecular  weights  are  expressed.  The  hydrogen 
atom  also  serves  as  the  unit  in  which  is  expressed  the 
capacity  that  one  atom  has  for  combining  with  other 
atoms.  This  capacity  is  called  valence. 

1  atom  of  chlorine  unites  with  1  atom  of  hydrogen 
forming  hydrochloric  acid  (HC1).  Hence  chlorine 
has  (in  this  instance)  a  valence  of  1. 

1  atom  of  oxygen  unites  with  2  atoms  of  hydrogen 
forming  water  (H,O).  Hence  oxygen  has  a  valence 
of  2. 

1  atom  of  zinc  unites  with  1  atom  of  oxygen  forming 
zinc  oxide  (ZnO).  Oxygen  has  a  valence  of  2,  hence 
zinc  has  a  valence  of  2.  Zinc  reacts  with  sulphuric 
acid  liberating  2  atoms  of  hydrogen  for  every  atom  of 
zinc  that  dissolves  ;  this  also  shows  that  zinc  has  a 
valence  of  2. 

Lead  forms  with  oxygen  PbO  and  PbO2,  hence  lead 
has  a  valence  of  2  and  of  4. 

Atoms  having  a  valence  of  1  are  said  to  be  univa- 
lent ;  of  2,  bivalent ;  of  3,  trivalent ;  of  i,  quadrivalent; 
of  5,  quinquivalent. 

The  following  list  shows  the  usual  valences  of  some 

27 


THE  NON-METALLIC  ELEMENTS. 


well-known  elements.  It  will  be  seen  that  certain 
elements  are  given  in  more  than  one  column.  This 
shows  that  these  elements  have  a  varying  valence. 


Univalent. 

Bromine  Br. 

Chlorine  01. 

.Fluorine  F. 

Hydrogen  H. 

Iodine  I. 

Silver  Ag. 

Sodium  Na. 

Potassium  K. 


Quadrivalent. 


Bivalent.  Trivalent. 

Calcium  Ca.     Aluminium    Al. 

Carbon  C.       Antimony       Sb. 

Copper  Cu.    Arsenic  As. 

Iron  Fe.     Boron  B. 

Lead  Pb.     Iron  Fe. 

Magnesium  Mg.    Nitrogen        N. 

Oxygen  O. 

Sulphur  S. 

Tin  Sn. 

Zinc  Zn. 

Quinquivalent. 


Carbon  C.  Antimony     Sb. 

Lead  Pb.  Arsenic         As. 

Silicon  Si.  Nitrogen       N. 

Tin  Sn.  Phosphorus  P. 

Write  the  symbols  of  the  following-named  com- 
pounds : 

(1)  lead  iodides  ;  (2)  potassium  oxide  ;  (3)  calcium 
sulphide ;  (4)  magnesium  iodide  ;  (5)  tin  bromides ; 
(6)  hydrogen  chloride ;  (7)  aluminium  chloride ;  (8) 
zinc  sulphide  ;  (9)  copper  bromide  ;  (10)  lead  chlorides  ; 
(11)  zinc  oxide  ;  (12)  silicon  oxide ;  (13)  antimony 
chlorides  ;  (14)  carbon  oxides  ;  (15)  phosphorus  chlo- 
rides ;  (16)  sodium  bromide  ;  (17)  sodium  sulphide  ; 
(18)  sodium  oxide;  (19)  calcium  oxide;  (20)  arsenic 
oxides  ;  (21)  aluminium  oxides  ;  (22  silver  bromide  ; 
(23)  boron  oxide. 


VALENCE.  29 

A  knowledge  of  valence  helps  us  10  write  the  sym- 
bols of  compounds  correctly.  Example  :  To  write  the 
symbol  silicon  fluoride,  we  consult  the  above  table  and 
find  that  silicon  has  a  valence  of  4 ;  fluorine  of  1. 
Hence  the  symbol  is  SiF4. 


EXERCISE  11. 
WATER. 

Water  has  the  symbol  H2O.  Write  the  reaction  that 
takes  place  when  hydrogen  burns.  How  many  grams 
of  hydrogen  must  you  burn  to  produce  a  gram  of 
water  ?  How  many  liters  of  hydrogen  ?  How  many 
grams  of  oxygen  will  be  consumed  ? 

(a)  Distribution. 

Heat  in  a  dry  test-tube  a  little  wood.  Try  the  same 
experiment  with  a  little  bread  ;  with  sugar.  What 
evidence  have  you  that  water  is  liberated  in  each 
case? 

(b)  Solution  in  Water. 

EXPLANATION  :  If  you  treat  pure  salt  with  water  in 
sufficient  quantity,  the  salt  disappears  and  you  obtain 
a  liquid  that  looks  like  pure  water.  The  taste  shows 
that  salt  is  present  in  solution.  If  you  add  a  crystal 
of  potassium  permanganate  to  sufficient  water,  the 
crystal  disappears  and  you  obtain  a  clear  but  highly 
colored  solution.  The  color  shows  that  the  perman- 
ganate is  present  in  the  solution.  On  the  other  hand, 
if  you  shake  finely  powdered  chalk  with  water  you  ob- 
tain a  milky  liquid  which  is  not  a  solution  since  the 
chalk  is  simply  suspended  in  the  water.  In  the  same 
way,  oil  and  water,  mixed,  do  not  give  a  solution,  as  the 

30 


WATER.  31 

oil  is  simply  suspended  in,  or  floats  on  the  surface  of, 
the  Water.  Alcohol,  however,  dissolves  in  water  form- 
ing a  clear  solution.  Examples  of  solution  :  hard  water, 
all  dilute  liquid  reagents,  clear  tea  and  coffee.  Exam- 
ples of  substances  suspended  in  liquids :  milk,  white- 
wash, dirty  water,  muddy  coffee. 

Evaporate  25  cc.  of  "  city  "  or  well  water,  free  from 
suspended  matter,  in  a  clean  evaporating-dish,  just  to 
dryness.  What  evidence  have  you  that  the  water  held 
solid  matter  in  solution  ?  Repeat  the  experiment 
using  distilled  water.  Kesults  ?  Why  do  we  use  dis- 
tilled water  in  the  laboratory  ? 

(c)  Conditions  affecting  Solution. 

(1)  State  of  Division. — Place  a  crystal  of  copper  sul- 
phate (-J  grm.)  in  a  test-tube  half  full  of  water  and 
shake  for  several  minutes  or  till  the  crystal  nearly 
dissolves.     Eepeat  using  the  same  volume  of  water 
and  £  grm.  finely  pulverized   copper  sulphate.      In 
which  case  is  solution  the  more  rapid  ? 

(2)  Temperature. — Add  2  grms.  ammonium  chloride 
to  5  cc.  water.     Shake   for  a  few  minutes.     Is  solu- 
tion complete  ?     Now  heat  to  boiling.     What  takes 
place  ?     Allow  to  cool  and  note  result.     What  effect 
does   heat   have    upon   the   solubility   of   most   sub- 
stances ? 

(d)  Saturated  Solution. 

This  may  be  prepared  as  follows  :  Put  100  cc.  of 
water  in  a  beaker  and  bring  into  solution  as  much 
common  salt  as  the  water  will  dissolve.  Make  use 
of  what  you  have  learned  in  the  last  section  in  regard 
to  state  of  division  and  temperature.  When  no  more 


32  THE  NON-METALLIC  ELEMENTS. 

of  the  salt  will  dissolve  allow  to  cool  to  the  tem- 
perature of  the  room.  A  little  salt  separates  out, 
and  you  have  a  saturated  solution.  Filter  from 
undissolved  salt,  evaporate  to  one  half  the  former 
volume,  and  cool.  What  has  separated  out?  What 
must  always  take  place  (if  no  chemical  change  oc- 
curs) when  you  concentrate  a  saturated  solution  ? 
Filter  the  salt  from  the  solution,  dry  on  filter-paper, 
and  preserve  for  future  use. 

(e)    Water  of  Crystallization ;    Water-free  Crystals. 

EXPLANATION  :  Many  substances  unite  with  definite 
amounts  of  water  in  the  process  of  crystallization. 
We  cannot  drive  off  this  water  without  destroying  the 
form  of  the  crystal.  On  the  other  hand,  many  sub- 
stances crystallize  without  water.  These  substances 
may,  and  commonly  do,  have  adherent  moisture  on 
the  surface  or  even  water  enclosed  mechanically  in 
the  crystal,  but  this  water  has  nothing  to  do  with  the 
structure  of  the  crystal  and  may  be  driven  off  without 
affecting  the  crystal's  form. 

Heat  a  little  (J  grm.)  pure  dry  salt  in  a  test-tube  and 
note  result. 

Heat  an  equal  amount  of  crystallized  sodium  sul- 
phate in  the  same  way.  Which  of  these  substances 
contains  water  of  crystallization  ? 

Try  the  same  experiment  with  each  of  the  follow- 
ing :  potassium  chloride,  copper  sulphate,  and  cobilt- 
ous  chloride.  Heat  the  last  two  substances  gradu- 
ally till  the  color  just  changes.  Cool  and  add  a 
drop  of  water.  Note  all  you  observe  and  expiain 
fully. 


WATER.  33 

(/)  Efflorescence. 

Expose  to  the  air  a  crystal  of  sodium  sulphate  in  a 
watch-glass.  Examine  after  some  time.  Explain. 
Bepeat  with  a  crystal  of  sodium  carbonate. 

(g)  Deliquescence. 

Treat  a  small  piece  of  calcium  chloride  and  of  po- 
tassium hydrate  as  you  did  the  substances  in  (/). 
What  do  you  observe  in  each  case  ?  (Note. — The  time 
required  for  any  marked  change  in  (/)  and  (g)  will 
depend  upon  the  amount  of  moisture  in  the  atmos- 
phere. If  the  air  is  dry,  breathe  over  the  substances. 
In  damp  weather  set  in  direct  sunlight,  in  closed 
window.) 

How  can  you  find  out  whether  a  liquid  holds  a  solid 
in  solution  ? 

Does  a  substance  that  is  entirely  insoluble  have 
any  taste  ? 


EXERCISE 


CHLORINE. 

All  work  with  chlorine  must  be  done  under  tlie  hood.    Avoid  in- 
haling the  gas. 

Put  25  grms.  of  manganese  dioxide  in  a  (250-cc.) 
flask,  fitted  with  a  cork,  a  delivery-tube,  and  a 
thistle-tube.  See  Fig.  15.  Add 
through  the  thistle-tube  enough 
concentrated  hydrochloric  acid  to 
cover  the  manganese  dioxide,  and 
shake  till  you  are  sure  that  all  of 
the  oxide  is  in  contact  with  the 
acid.  Warm  gently  on  a  wire 
gauze,  taking  care  not  to  boil. 


0 


=#£>m 


Eeaction  :  MnOa  +  4HC1  = 


Mn01 


2H20 


01,. 


It 


I 


FIG.  15. 


Collect  several  bottles  for  study 
by  displacement  of  air.  Try  to 
collect  one  bottle  by  displace- 
ment of  water.  Which  is  the 
better  way.?  Why  ? 

(a)  In  one  bottle  place  two 
pieces  of  calico  (preferably  red),  orte  wet,  and  the 
other  dry  ;  a  small  piece  each  of  written  (ink)  and 
printed  paper,  both  wet  ;  a  wet  .green  leaf  or  flower. 
Does  moisture  aid  the  bleaching  action  of  chlorine  ? 
From  which  of  the  substances  is  the  color  discharged  ? 
Conclusion  ? 

(b)  Dissolve  the  gas  in  another  bottle  by  shaking 

34 


CHLORINE.  35 

with  20  cc.  of  water.  Pour  half  of  this  solution  into 
10  cc.  of  a  dilute  solution  of  some  vegetable  color,  as 
indigo.  Is  the  color  discharged?  Pour  the  rest  of 
the  chlorine-water  into  a  solution  of  potassium  bi- 
chromate. Does  chlorine  seem  to  have  the  same  effect 
on  mineral  as  on  vegetable  colors  ? 

(c)  Into  another  bottle  of  the  gas  sprinkle  a  little 
powderecL.  antimony.      One   atom   of   antimony   (Sb) 
unites  with  three  atoms  of  chlorine.     Write  the  re- 
action.    What  is  the  name  of  the  product  formed  ? 

(d)  Into  another  bottle  of  chlorine  introduce  a  strip 
of  filter-paper   that  has   been   treated   with  a   drop 
of  warm  oil  of  turpentine.     What  takes  place  ?     Tur- 
pentine is  composed  of  carbon  and  hydrogen.     With 
which  of  these  elements  has  chlorine  united  ? 

Other  methods  of  making  chlorine : 

(1)  Warm  in  a  test-tube  a  very  small  amount  of  a 
mixture  of  salt  and  manganese  dioxide,  with  a  few 
drops  of  dilute  sulphuric  acid.     Test  the  escaping 
gas  with  a  piece  of  wet  calico. 

(2)  Warm  a  little  potassium  bichromate  with  con- 
centrated hydrochloric  acid,  and  test  as  in  (1). 

(3)  Put  1  cc.  water  in  a  test-tube  and  add  the  same 
amount  of  concentrated  sulphuric  acid.     Treat  a  little 
fresh    bleaching-powder    with    this    acid.      What    is 
liberated  ? 

Will  chlorine  burn?  Will  it  support  combustion? 
Is  it  soluble  in  water  ?  How  is  it  prepared  commer- 
cially ?  What  are  its  uses  ? 

How  much  chlorine  can  be  made  from  60  grms. 
salt  ?  How  much  manganese  dioxide  will  be  required  ? 

References :  Clk.,  pp.  111-117  ;  Cly.,  pp.  70-74;  K., 
pp.  95-100  ;  S.,  pp.  92-96  ;  S.  and  L.,  pp.  79-84  ;  W., 
pp.  202-207. 


EXERCISE  13. 

HYDROCHLORIC  ACID  (HC1). 

Add  30  cc.  of  concentrated  sulphuric  acid  to  10  cc.  of 
water  in  a  beaker.     While  the  acid  is  cooling  set  up 
apparatus  as  shown  in  Fig.  15,  connect- 
=    ing   at   A    the    absorption    apparatus 
(Fig.  16)  instead  of  the  delivery-tube. 
Put  20  cc.  of  water   in    the  first,  and 
several  times  as  much  in  the  second, 
bottle.      The  tubes   should   not  quite 
reach  the  surface  of  the  water.     Put 
25    grms.    salt   in    the    flask,   replace 
stopper  and  tubes,  and,  when  the  ap- 
paratus is  in  order,  pour  the  sulphuric 
acid  through  the  thistle-tube  and  warm 
16  Sen^y-    When  the  gas  comes  off  freely, 

disconnect   at  A  long  enough  to  per- 
form the  following  experiments : 

(a)  Blow  across  the  tube  where  the  gas  is  escaping. 
What  effect  does  the  gas  have  on  the  moisture  in  your 
breath? 

(b)  Test  the  escaping  gas  with  a  lighted  splinter. 
Does  it  burn  ?     Does  it  support  combustion  ? 

(c)  Does  it  affect  red  or  blue  litmus  paper  ? 

(d)  Put  two  or  three  drops  of  ammonia  on  filter- 
paper  and  hold  in  the  escaping  gas.     What  happens? 

Now  connect  a  delivery-tube  at  A,  as  in  Fig.  15,  and 

36 


HYDROCHLORIC  ACID.  37 

collect  the  gas  in  a  dry  bottle,  by  displacement  of 
air.  Breathe  across  the  mouth  of  the  bottle  to  deter- 
mine when  it  is  full  of  the  gas.  Cover  with  a  glass 
plate  and  invert  it  in  water  in  a  pneumatic  trough. 
Kernove  the  plate  and  note  what  happens.  Replace 
the  plate  below  the  surface  of  the  water,  and  remove 
the  bottle  and  contents.  Test  the  liquid  with  red  and 
with  blue  litmus  paper.  Place  a  drop  on  the  tongue. 
Taste  ?  Connect  the  flask  again  at  A  with  the  absorp- 
tion apparatus  and  continue  heating  till  no  more  gas 
is  given  off.  Allow  the  flask  to  cool.  It  contains 
crystals  of  acid  sodium  sulphate  (HNaSOj.  Now 
complete  the  reaction : 

NaCl  +  H2SO4  =  .  .  . 

Test  a  little  of  the  liquid  in  the  first  bottle,  in 
separate  test-tubes,  with  each  of  the  following :  iron 
filings,  zinc,  and  manganese  dioxide  (warm).  What 
takes  place  in  each  case  ?  Reactions  ? 

Test  the  liquid  with  red  and  with  blue  litmus  paper. 
To  a  little  of  the  same  solution  (first  bottle)  add 
in  separate  tests  a  few  cc.  of  the  following  solutions : 
silver  nitrate  (AgNO3),  mercurous  nitrate  (HgNO,), 
and  lead  nitrate  (Pb(NO3)2).  Write  reactions  noting 
that  1  molecule  of  lead  nitrate  reacts  with  2  mole- 
cules of  hydrochloric  acid,  while  each  of  the  other 
nitrates  reacts  with  1. 

Allow  the  lead  chloride  to  settle  and  pour  off 
the  liquid  as  completely  as  possible  without  dis- 
turbing the  solid.  Add  a  few  drops  of  water  and 
heat  to  boiling,  continuing  the  process  till  solution 
is  just  effected.  Allow  to  cool.  What  do  you  observe  ? 
What  do  you  conclude  as  to  relative  solubility  of  lead 
chloride  in  hot  and  in  cold  water  ? 


38  THE  NON-METALLIC  ELEMENTS. 

Other  methods  of  preparing  hydrochloric  acid  : 
(1)  Treat  a  little  ammonium  chloride  in  a  test-tube 
with  concentrated  sulphuric  acid  and  test  the  escaping 


(2)  Treat  a  little  potassium  chloride  in  the  same 
way. 

(3)  Add  a  little  concentrated  sulphuric  acid  to  a 
little  concentrated  hydrochloric  acid  from  the  bottle 
on   your  desk.     Is  the    hydrochloric   acid  displaced 
from    its    solution    (concentrated   hydrochloric    acid 
means  a  strong  solution  of  the  gas  in  water)  by  sul- 
phuric acid? 

Beferences  :  Clk.,  pp.  118-121 ;  Cly.,  pp.  76-80  ;  E., 
pp.  103-108;  S.,  pp.  97-98;  S.  andL.,  pp.  68-71 ;  W., 
pp.  110-114 


EXERCISE  14. 

CLASSIFICATION  OF  CEKTAIN  COMPOUNDS. 

For  convenience  many  compounds  (by  no  means  all)  can  be  classi- 
fied as  acids,  bases,  and  salts,  or  as  simple  derivatives  of  these. 

(a)  ACIDS. — Write   the  names  and  formulas  of  the 
three  acids  that  you  have  used'in  these  exercises.  Find 
the  names  and  formulas  of  five  other  acids  in  your  text- 
book.    What  element  is  present  in  all  acids  ?     Put  a 
drop  of  sulphuric  acid  in  25  cc.  of  distilled  water, 
moisten  a  glass  rod  with  this  diluted  acid,  and  taste. 
Repeat  the  same  experiment,  using  nitric  acid  instead 
of  sulphuric  acid.     Test  each  with  red  and  with  blue 
litmus  paper.    Results?    (Note. — Use  very  small  pieces 
of  litmus  paper,  a  fresh  piece  for  each  test.)     Now 
tell  all   you   can   about  the   characteristics  of  acids. 
Does  your  description  apply  to  all  (as  very  weak  or 
insoluble)  acids  ?    To  answer  this,  test  as  above  a  little 
of  a  stearine  candle  (which  consists  largely  of  stearic 
acid).     Eesults  ? 

(b)  BASES. — Try  the  action  of  each  of  the  following 
solutions  with  litmus  paper :  sodium  hydrate,  potas- 
sium   hydrate,     ammonium     hydrate    ("  ammonia "), 
barium  hydrate,  and  calcium  hydrate  ("  lime-water  "). 
What  do  you  observe  ? 

Put  a  little  solid  magnesium  oxide  on  red  litmus 
paper  and  moisten ;  allow  to  stand  .several  minutes. 
Is  the  litmus  changed  ?  Taste  a  drop  of  very  dilute 
solution  of  sodium  hydrate ;  of  calcium  hydrate.  What 


40  THE  NON-METALLIC  ELEMENTS. 

have  you  learned  about  bases  ?  Do  these  character- 
istics apply  to  insoluble  or  very  weak  ba^es  or  basic 
oxides  ?  To  answer,  test  the  action  of  moistened  zinc 
oxide  or  copper  oxide  on  red  litmus  paper. 

(c)  SALTS. — Dissolve  a  little  pure  sodium  chloride  in 
distilled  water  in  a  clean  test-tube  and  test  the  solu- 
tion with  litmus  paper  of  both  colors.  Is  either 
affected  ?  Kepeat  with  potassium  chloride;  magnesium 
sulphate;  sodium  sulphate;  potassium  nitrate. 

Dissolve  2  grms.  sodium  hydrate  in  5  cc.  water  in  an 
evaporating-dish  by  the  aid  of  gentle  heat.  Add  di- 
lute hydrochloric  acid  1  cc.  at  a  time  till  the  solution 
is  just  neutral.  After  each  addition,  test  in  the  follow- 
ing way  :  A  glass  rod,  drawn  to  a  point,  is  dipped  into 
the  solution  ;  the  point  is  placed  on  blue  litmus  paper. 
As  soon  as  the  acid  is  in  excess  the  spot  where  the  rod 
touches  becomes  red.  Stir  to  be  sure  that  the  solu- 
tion is  well  mixed  and  test  again.  If  still  red,  you 
have  acid  in  excess.  Now  add  cautiously  sodium  hy- 
drate from  the  reagent  bottle,  drop  by  drop,  stirring 
well  and  testing  after  each  addition,  till  the  solution 
changes  neither  red  nor  blue  litmus.  If  you  acci- 
dentally add  a  trifle  too  much  sodium  hydrate,  neu- 
tralize with  a  very  dilute  acid  solution.  Filter  if  the 
solution  is  not  perfectly  clear  and  evaporate  to  about 
one  half  the  former  volume.  Now  test  again  with  lit- 
mus to  make  sure  that  you  made  no  error  when  you 
decided  that  the  solution  was  neutral.  If  not  per- 
fectly neutral,  neutralize.  Now  place  the  dish  on  a 
wire  gauze  and  evaporate  to  dryness  over  the  open 
flame.  What  is  the  substance  ?  Eeaction  by  which 
it  is  made  ?  Weigh  it.  If  you  used  exactly  2  grms. 
of  sodium  hydrate,  how  much  salt  ought  you  to  get  by 
the  above  reaction  ? 


CLASSIFICATION  OF  CERTAIN  COMPOUNDS.       41 

Do  all  salts  give  a  neutral  reaction  with  litmus  ? 
Test  (in  solution)  sodium  carbonate,  potassium  car- 
bonate, copper  sulphate,  alum,  and  iron  (ferric)  chlo- 
ride. Do  weak  acids  perfectly  neutralize  the  strong 
basic  properties  of  sodium  and  potassium  ?  Does 
weakly  basic  iron  counteract  the  acid  properties  of 
chlorine  in  ferric  chloride  ? 

References  :  Clk.,  p.  61  ;  Cly.,  pp.  43-47;  K,  ppl 116- 
132  ;  S.,  pp.  75-79  ;  S.  and  L.,  pp.  58-62  ;  W.,  pp.  89- 
96. 


EXERCISE  15. 
«  NlTBOGEN. 

Nearly  pure  nitrogen  can  be  obtained  from  the  air  by  burning  phos- 
phorus in  a  closed  vessel.  Phosphorus  should  be  kept  and  cut  under 
water.  Handle  with  pincers,  and  throw  all  unconsumed  pieces  in 
the  slop-jar.  After  using,  heat  the  deflagrating-spoon  to  ignite  any 
pieces  that  may  adhere  to  it. 

Make  a  deflagrating-spoon  with  some  copper  wire 
and  a  piece  of  crayon  hollowed  at  one  end.  Bend  in 
the  shape  shown  in  Fig.  17. 

Place  a  piece  of  phosphorus  as  large  as  a  pea  in  the 
cup  of  the  spoon.  Light  the  phosphorus,  in- 
sert in  an  inverted  bottle,  and  immediately 
immerse  the  mouth  of  the  bottle  about  an 
inch  below  the  surface  of  the  water  in  the 
pneumatic  trough.  A  little  air  is  first  driven 
out.  Why  is  this  ?  Note  carefully  the  burn- 
ing. The  white  fumes  are  phosphorus 
pentoxide  (P2O6).  In  a  short  time  the  cloud 
disappears.  Where  does  it  go  ?  Why  does 
the  water  rise  in  the  bottle  ?  What  proportion  of 
the  air  remains  ?  What  has  become  of  the  oxygen  ? 
Allow  the  bottle  to  stand  in  the  water  for  fifteen 
minutes,  then  slip  a  glass  plate  under  the  bottle  below 
the  surface  of  the  water  and  invert  the  bottle  and 
its  contents. 

Has  nitrogen  any  color,  odor,  or  taste  ?  Will  it 
burn?  Will  it  support  combustion?  Test  with  a 

43 


NITROGEN.  43 

glowing  splinter ;  also  with  burning  sulphur.  Is 
nitrogen  chemically  active  ? 

Consult  your  text  if  necessary  in  answering  the  fol- 
lowing questions : 

What  purpose  does  nitrogen  serve  in  the  air  ?  How 
can  it  be  shown  that  air  is  a  mixture  and  not  a  com- 
pound ?  What  part  of  the  air  is  nitrogen,  by  volume 
and  by  weight  ?  Is  nitrogen  lighter  or  heavier  than 
air  ?  than  oxygen  ? 

References:  Clk.,  pp.  49-54;  Cly.,  pp.  115,  116, 
124-126  ;  K.,  pp.  126-128  ;  S.,  pp.  50,  51,  82-85  ; 
S.  and  L.,  pp.  10-14,  18-20  ;  W.,  pp.  26-30,  185-189. 


EXERCISE  16. 
AMMONIA. 

Set  up  apparatus  as  in  Exercise  13,  without  the 
thistle-tube.  See  Figs.  15  and  16.  Use  an  asbestos 
plate  instead  of  the  wire  gauze.  Place  10  grms.  of 
quicklime  (free  from  air-slaked  lime  and  stone)  in 
the  flask,  add  10  cc.  water  and  warm  gently.  Allow  to 
cool  and  add  15  grms.  of  ammonium  chloride.  Mix 
by  cautiously  shaking. 

Set  up  and  fill  the  absorption  apparatus  exactly  as 
in  Exercise  13.  Now  heat,  and  when  the  gas  comes 
off  freely  disconnect  at  A  long  enough  to  perform  the 
following  experiments : 

(a)  Test  the  escaping  gas  with  a  glowing  splinter. 
Does  it  burn  ?  Does  it  support  combustion  ? 

(6)  Test  it  with  red  and  with  blue  litmus  paper. 
Kesults  ? 

(c)  Collect  a  bottle  of    ammonia  just  as  you  col- 
lected  hydrochloric    acid,    by    displacement    of    air- 
holding,  however,  the  mouth  of  the  bottle  downward. 
Let  the  tube  reach  up  almost  to  the  bottom  of  the 
bottle.     To  tell  when  full,  test  with  a  piece  of  moist- 
ened red  litmus  paper  held  near  the  mouth    of   the 
bottle.     Test  the  solubility  as  you  did  in  the  case  of 
hydrochloric  acid. 

(d)  Is  ammonia  lighter  or  heavier  than  air?     Does 
the  gas  seem  to  diffuse  upward  or  downward  most 
rapidly  as  it  escapes  at  A?     Test  with  litmus. 

44 


AMMONIA.  45 

Now  connect  the  absorption  apparatus  and  continue 
to  heat  as  long  as  gas  comes  off  freely.  Too  long 
heating  is  liable  to  crack  the  flask. 

The  first  bottle  should  contain  a  strong  solution  of 
ammonia  in  water.  Since  this  solution  acts  v§ry  much 
like  potassium  hydrate,  we  assume  that  ammonium 
hydrate  has  been  formed  according  to  the  reaction : 
NHS  +  H3O  =  NH4OH. 

Divide  the  solution  into  two  parts.  Neutralize  one 
with  hydrochloric  acid  and  evaporate  to  dryness  over 
a  low  flame.  "What  remains  ?  Reaction  by  which  it 
was  formed  ?  Heat  a  little  in  a  dry  test-tube.  What 
collects  on  the  sides  of  the  test-tube  ?  This  process 
is  called  sublimation.  Treat  a  little  of  the  sublimate 
in  a  test-tube  with  sodium  hydrate  solution  and  warm. 
Odor  given  off? 

Neutralize  the  other  half  of  the  ammonium  hydrate 
solution  with  dilute  sulphuric  acid,  Eeaction  ?  Evap- 
orate and  test  the  residue  with  sodium  hydrate.  What 
is  given  off  ?  How  did  you  recognize  it  ?  Complete 
the  reaction  :  2NaOH  +  (NH4)2SO4  =  .  .  . 

Note. — In  case  your  ammonium  hydrate  solution  proves  too  weak 
to  give  the  salts  in  sufficient  quantity,  use  the  ammonia  solution  on 
your  desk  for  neutralization  with  the  acids. 

Has  ammonia  any  odor  or  color  ?  Has  it  neutral, 
acid,  or  basic  properties  ?  Compare  it  with  hydrogen 
and  with  nitrogen.  Does  it  resemble  the  elements  of 
which  it  is  composed?  What  is  the  source  of  the 
ammonia  of  commerce  ?  What  are  some  of  the  uses 
of  ammonia  ? 

References:  Clk.,  pp.  53-57;  Cly.,  pp.  117,  118; 
R.,  pp.  133-141 ;  S.,  pp.  52-58;  S.  and  L.,  pp.  62-67  ; 
W.,  pp.  133-138. 


EXERCISE  17. 


The   apparatus 
shown  in  Fig.  18. 


NITRIC  ACID. 

used  in  preparing  nitric  acid  is 
The  retort  should  be  small  (100  to 
200  cc.).  Place  in  the  retort  15 
grms.  sodium  nitrate  and  10  cc. 
concentrated  sulphuric  acid.  Fill 
the  beaker  containing  the  test- 
tube  nearly  full  of  cold  water. 
Now  heat  the  gauze  gently,  as 
long  as  a  liquid  collects  in  the 
test-tube  used  as  a  receiver ;  then 
remove  the  burner  and  allow  the 
retort  to  cool.  Note  the  color  and 
odor  of  the  liquid  collected.  Is 
it  the  same  compound  as  the  con- 
centrated nitric  acid  on  your  desk?  Try  the  action 
of  a  few  drops  of  each  (diluted  with  a  little  water)  on 
copper.  Place  a  small  piece  of  finger-nail  in  a  drop 
of  the  undiluted  acid  and  note  the  color  after  washing 
with  water.  The  same  result  is  produced  on  many 
animal  substances. 

Nitric  acid  is  colorless.  The  reddish-brown  gas 
seen  in  the  retort  and  receiver  is  nitrogen  dioxide. 
The  nitric  acid  may  be  colored  by  some  of  this  sub- 
stance in  solution.  When  the  retort  is  cool,  pour  in  a 
little  water  and  heat  carefully,  adding  more  water, 
1  cc.  at  a  time,  till  the  substance  (NaHSO4)  is  dis- 

46 


FIG.  18. 


NITRIC  ACID.  47 

solved.  Filter  the  solution  thus  obtained.  If  you 
have  not  added  too  much  water,  crystals  will  separate 
out  on  cooling.  If  none  appear,  concentrate  by  evap- 
oration (one  half  former  volume)  and  cool  again.  When  a 
good  crop  of  crystals  is  obtained,  pour  off  the  liquid, 
redissolve  the  crystals  in  as  small  a  quantity  as  possi- 
ble of  distilled  water,  and  crystallize  as  before.  Pour 
off  the  liquid  and  dry  crystals  on  filter-paper.  Dis- 
solve one  or  two  in  distilled  water.  Is  the  solution 
acid,  basic,  or  neutral?  Label  the  crystals  sodium 
bisulphate  and  hand  them  to  your  instructor.  Com- 
plete the  reaction  :  NaNO3  +  HaSO4  =  NaHSO4  +  .  .  . 

Sodium  bisulphate  is  an  acid  salt.  Compare  its 
symbol  with  the  symbol  of  sodium  sulphate  and  of 
sulphuric  acid. 

Now  explain  what  is  meant  by  the  term  "  acid  salt." 

Action  of  Nitric  Acid  on  Metals. 

(a)  How  did  you  make  hydrogen  from  sulphuric 
acid  ?  From  hydrochloric  acid  ?  Can  you  make 
hydrogen  by  the  action  of  nitric  acid  on  a  metal  ? 
Try  with  zinc  ;  with  iron.  Test  the  escaping  gas  in 
each  case.  Can  you  detect  hydrogen  ?  Nitric  acid  is 
a  good  oxidizing  agent.  It  oxidizes  the  hydrogen  to 
water. 

(&)  Place  a  little  tin  in  a  test-tube  and  just  cover  with 
concentrated  nitric  acid.  Heat  gently.  If  action  does 
not  begin  at  once,  add  a  few  drops  of  water  and  warm 
again.  Examine  the  substance  left.  It  is  a  compound 
consisting  mostly  of  tin  and  oxygen,  the  latter  derived 
from  the  nitric  acid. 

What  are  some  of  the  most  important  salts  of  nitric 
acid  ?  How  are  they  obtained  ?  What  use  is  made 
of  nitric  acid  in  the  manufacture  of  high  explosives  ? 


48  THE  NON-METALLIC  ELEMENTS. 

PROBLEMS. 

(1)  How  much  nitric  acid  can  be  made  from  150 
grms.  of  sodium  nitrate  ? 

(2)  From  the  same  quantity  of  potassium  nitrate  ? 

(3)  300  grms.  nitric  acid  are  required;  how  much 
sodium  nitrate  must  be  used? 

(4)  How  much  sodium  bisulphate  will  be  formed  in 
Problem  3? 

References  :  Clk.,  pp.  58-60  ;  Cly.,  pp.  119,  120  ;  K., 
pp.  143-148  ;  S.,  pp.  67-70  ;  S.  and  L.,  pp.  55-57 ; 
W.,  pp.  116-122. 


EXERCISE  18. 


COMPOUNDS  OF  OXYGEN  AND  NITROGEN. 

(a)  Nitrous  Oxide  (N,0). 

Set  up  apparatus  as  shown  in  Fig.  11.  Heat  in  the 
test-tube  5  grms.  of  ammonium  nitrate  till  it  seems  to 
boil.  Drive  off  the  gas  at  as  low  a  temperature  as 
possible  and  collect  in  bottles  by  displacement  of 
water.  Allow  the  bottles  to  stand  in  water  for  fifteen 
minutes  before  examining ; 
then  test  color,  odor,  and 
taste.  Will  the  gas  burn? 
Will  it  support  combus- 
tion? Is  it  soluble  in 
water  to  any  marked  ex- 
tent? 

Complete   the   reaction 
NH4NO,  (heated)  =  .  .  . 

(b)  Nitric  Oxide  (NO). 

Use  apparatus  shown 
in  Fig.  19.  Put  15  grms. 
of  copper  in  the  flask  and 
add  dilute  nitric  acid 
through  the  thistle-tube. 
Collect  the  gas  by  displacement  of  water.  Add  the 
acid  a  little  at  a  time  so  that  the  gas  may  come  off 
gradually.  Warm  a  little  now  and  then,  regulating 

49 


FIG.  19. 


50  THE  NON-METALLIC  ELEMENTS. 

the  supply  of  acid  and  tlie  temperature  so  as  to 
produce  a  regular  evolution  of  gas.  If  the  gas  begins 
to  come  off  too  rapidly,  pour  in  cold  water  through 
the  thistle-tube. 

Eeaction  :  3Cu+8HNO1  =  3Cu(NO,)1+4H1O+2NO. 

Test  the  properties  of  nitric  oxide.  Will  it  burn  ? 
Will  it  support  combustion? 


(c)  Nitrogen  Peroxide 

Turn  upwards  one  of  the  bottles  containing  the 
colorless  nitric  oxide  just  obtained  and  uncover.  The 
gas  absorbs  oxygen  from  the  air  and  becomes  the 
reddish-brown  nitrogen  peroxide.  Write  the  reaction. 
Does  nitrogen  peroxide  burn  ?  Does  it  support  com- 
bustion ?  Is  it  soluble  in  water  ?  Add  a  little  water 
to  a  bottle  of  the  gas,  cover  with  the  hand,  and  shake 
well.  Does  the  color  disappear?  Now  explain  the 
colored  appearance  of  the  gas  in  the  flask  used  in 
preparing  nitric  oxide,  and  the  fact  that  a  colorless 
gas  was  collected  by  displacement  of  water. 

Which  of  the  compounds  studied  in  this  exercise 
most  resembles  oxygen?  How  can  you  explain  the 
fact  that  the  one  that  contains  the  smallest  per  cent 
of  oxygen  is  the  only  one  that  you  found  to  be  a 
supporter  of  combustion  ? 

(e)  The  Law  of  Multiple  Proportions 
is  well  illustrated  by  the  compounds  studied  in  (a), 
(b),  and  (c).  We  will  assume  that  nothing  is  known 
about  atoms,  molecules,  and  symbols.  All  that  we 
need  to  know  is  that  we  have  three  distinct  com- 
pounds (not  mixtures),  each  composed  of  oxygen  and 
nitrogen.  It  can  be  shown  that  heated  copper  has 
the  property  of  absorbing  all  the  oxygen  in  any  of 


COMPOUNDS  OF  OXYGEN  AND  NITROGEN.       51 

them,  leaving  behind  all  the  nitrogen.     If  we  make 
such  an  analysis  in  each  case  we  shall  obtain  the  fol- 
lowing results : 
in  11  grms.  nitrous )      7    grms.    nitrogen,    4    grins. 

oxide,  )  oxygen, 

in    15    grms.    nitric  )      7    grms.    nitrogen,    8    grms. 

oxide,  )  oxygen, 

in  23  grms.  nitrogen  |      7   grms.    nitrogen,    16  grms. 

peroxide,  j  oxygen. 

How  can  the  simple  ratio  4  :  8  : 16  (1 :  2  :  4)  be  ex- 
plained? Answer:  By  assuming  that  compounds  are 
made  up  of  simple  units  or  atoms.  Hence  the  simple 
ratio  of  weights  is  to  be  explained  by  assuming  a 
simple  ratio  in  the  numbers  of  the  atoms  in  the 
compounds. 

That  the  weight  relations  just  considered  are  in 
harmony  with  the  molecular  weights  as  derived  from 
the  symbols  given  in  the  exercise  can  be  readily  seen 
from  the  following : 

nitrous  oxide,          7  :    4  =  14  +  14  : 16    .     .     .     N2O. 
nitric  oxide,  7:8=  14  : 16    ...     NO. 

nitrogen  peroxide,  7  : 16  =  14  : 16  +  16    .     NOa. 

State  the  law  of  multiple  proportions. 


EXERCISE  19. 

CARBON. 

Heat  in  a  porcelain  or  metal  crucible  one  piece 
each  of  hard  and  of  soft  wood  covered  with  sand. 
Light  the  gas  above  the  sand.  Does  the  charcoal 
from  the  different  woods  differ  in  physical  properties  ? 
Put  a  little  powdered  charcoal  on  platinum  foil  and 
heat  strongly.  Does  it  burn  ?  Try  the  same  experi- 
ment with  graphite  (another  form  of  carbon)  from 
your  pencil.  Is  carbon  active  at  ordinary  tempera- 
tures? Is  it  attacked  by  acids  or  alkalies?  Try 
with  those  on  your  desk.  Carbon  in  the  form  of 
"  lamp-black "  is  used  in  preparing  printer's  ink. 
Why  is  printer's  ink  as  well  as  India  ink  so  perma- 
nent? 

Name  and  describe  three  allotropic  forms  of  carbon. 

(a)  Charcoal  as  an  Absorbent. 

To  a  test-tube  one  third  full  of  water  add  indigo  solu- 
tion till  the  water  is  distinctly  blue.  Now  add  1  grm.  of 
animal  charcoal  and  heat,  constantly  shaking  for  sev- 
eral minutes.  Filter,  and  note  whether  the  blue  color 
has  disappeared. 

Kepeat  the  experiment,  using  litmus  solution  instead 
of  indigo.  Results? 

Dilute  hydrogen  sulphide  water  till  the  odor  is 
only  just  distinctly  noticeable.  Shake  with  animal 
charcoal  and  note  odor  before  and  after  shaking. 

53 


CARBON.  53 

Eesults  ?  What  do  you  conclude  from  these  experi- 
ments concerning  the  absorbent  power  of  carbon  in 
the  form  of  animal  charcoal? 

(b)  Carbon  as  a  deducing  Agent. 

(1)  Mix  by  grinding  in  a  mortar  3  grms.  of  powdered 
copper  oxide  with  0.2  grm.  of  wood  charcoal.     Put  in 
a  small  porcelain   crucible  and  cover 

with  a  very  thin  layer  of  pulverized 
charcoal,  then  place  the  crucible  cover 
on  the  crucible  to  protect  the  mixture 
from  the  action  of  the  air.  Place  the 
crucible  and  its  contents  on  a  wire  or 
pipe  triangle,  and  heat  strongly  for 
five  minutes  with  Bunsen  or  gasoline 
burner.  See  Fig.  20.  (Few  alcohol- 
lamps  give  sufficient  heat  for  this  reac-  ^  FIG 
tion.)  Cool  and  examine  the  contents 
of  crucible.  Has  the  copper  oxide  been  reduced  to 
copper  ? 

Try  the  action  of  some  of  the  reddish  substance 
with  nitric  acid.     Complete  the  reaction 

2CuO  +  C  =  CO,  +  . .  . 

(2)  Heat  a  little  lead  oxide  (PbO)  on  charcoal  before 
the   blowpipe.     (The   use   of    the   blowpipe   is   fully 
described  in  most  works  on  chemistry.     See  index  in 
text  or  reference-books.)     Is  the  lead  oxide  reduced 
by   the    heated   charcoal?      Complete    the    reaction 
2PbO  +  C  =  .  .  . 

(c)   Test  for  Carbon. 

Carbon  is  most  readily  detected  by  burning  it  to 
carbon  dioxide.     Make  several  bottles  of  oxygen  as 


54  TEE  NON-METALLIC  ELEMENTS. 

in  Exercise  6.     Cover  with  greased  glass  plates  and 
reserve  for  the  following  experiments  : 

(1)  Fasten  a  piece  of  charcoal  to  a  piece  of  wire, 
heat  to  glowing,  and  burn  in  a  bottle  of  oxygen.     As 
soon  as  the  charcoal  ceases  to  glow,  add  5  cc.  of  clear 
lime-water  and  shake.     What  do  you  notice  ? 

Keaction  :  Ca(OH)2  +  CO,  =  CaCO3  +  H,O. 
CaCO3    is    insoluble     in   water,   hence   the   liquid 
becomes  turbid. 

(2)  Kepeat  the  experiment,  using  a  piece  of  candle 
instead  of  charcoal.     Does  the  candle  contain  carbon  ? 
Why  do  you  think  so?     How  would  it  be  possible  to 
prove  that  the  diamond  is  carbon  ? 

References:  Clk.,  pp.  74-79;  Cly.,  pp.  147-152;  R, 
pp.  156-167 ;  S.,  pp.  125-131 ;  S.  and  L.,  pp.  166-176 ; 
W.,  pp.  44-52. 


EXERCISE  20. 

COMPOUNDS  OF  CARBON  AND  OXYGEN. 

(a)  Carbon  Dioxide. 

Set  up   apparatus   consisting  of   a  large  test-tube 
carrying    a   thistle-tube    and    a    delivery-tube.      See 
Fig.  21.     Put   a   little  solid  sodium  car- 
bonate into  the  test-tube  and  add  dilute 
hydrochloric    acid  through  the    thistle- 
tube.     Pass  the  escaping  gas   into   lime- 
water. 

Now  try  in  separate  tests  the  action  of 
sodium  carbonate  with  dilute  sulphuric, 
nitric,    and    acetic    acids.      Does   a   gas 
escape  which  renders  lime  water  turbid  in       FIG.  21. 
each  case  ? 

Try  the  action  of  marble  (calcium  carbonate)  with 
each  of  the  acids  mentioned  above.  Is  the  same  gas 
liberated  as  before  ? 

Complete  the  reactions : 

NatCO,  +  2HC1  =  HaO  +  .  .  . 
Na,COs  +  H2S04  =  H20  +  .  .  . 
Na2CO,  +  2HNO,  =  HaO  +  .  . » 

Note  that  calcium  replaces  two  atoms  of  hydrogen 
and  complete  the  following : 

CaC03  +  2HC1 
CaCO,  +  H2SO4    =  .  .  . 

CaCO,  +  2HN03 

55 


56  THE  NON-METALLIC  ELEMENTS. 

Prepare  carbon  dioxide  for  study  by  the  action  of 
hydrochloric  acid  on  marble.  Use  apparatus  shown 
in  Fig.  15,  and  collect  the  gas  by  displacement  of  air. 
Will  the  gas  burn  or  support  combustion  ?  Test  with 
a  lighted  splinter.  Is  it  lighter  or  heavier  than  air? 
Pour  it  as  you  would  water  on  a  lighted  splinter. 
Kesult  ?  Pour  the  gas  in  one  bottle  into  another,  and 
test  for  carbon  dioxide  in  the  second  bottle  with  a 
burning  splinter.  Is  carbon  dioxide  soluble  in  water  ? 
Test  as  follows  :  Collect  a  bottle  of  the  gas  by  dis- 
placement of  air.  Now  remove  deli  very- tube  and 
insert  a  thistle-tube  through  the  hole  in  the  paste- 
board cover.  Fill  the  bottle  one  third  full  of  cold 
water  through  the  thistle-tube.  Remove  tube  and 
cover,  close  tightly  with  the  hand  and  shake  vigor- 
ously for  a  minute  or  two.  After  putting  the  mouth 
of  the  bottle  under  water,  remove  the  hand  and  note 
result. 

Dissolve  2  grms.  of  solid  sodium  hydrate  in  10  cc. 
distilled  water  and  allow  to  cool.  Place  in  a  test- 
tube  and  pass  in  carbon  dioxide  rapidly.  Does  the 
solution  become  warm?  After  the  gas  is  no  longer 
absorbed  test  the  solution  with  acids.  Does  it  behave 
like  a  solution  of  sodium  carbonate  ? 

Complete  the  reaction  : 

2NaOH  +  CO,  =  .  .  . 

Why  do  you  get  a  precipitate  with  calcium  hydrate 
and  not  with  sodium  hydrate  ?  Compare  the  solubil- 
ity of  the  two  carbonates. 

Pass  your  breath  through  a  solution  of  calcium 
hydrate  in  a  test-tube.  What  does  this  show  ?  Allow 
a  little  of  the  hydrate  solution  to  stand  exposed  to  the 


COMPOUNDS  OF  CARBON  AND   OXYGEN.          57 

air  for  several  hours.     What  evidence  have  you  that 
the  air  contains  carbon  dioxide  ? 

What  use  is  made  of  carbon  dioxide  by  growing 
plants  ?  (See  text.) 

(b)  Carbon  Monoxide. 

Connect  to  the  apparatus  used  in  generating  car- 
bon dioxide  (Fig.  15)  a  wash-bottle  such  as  you 
used  in  purifying  hydrogen  (Fig.  14).  Put  into  the 
flask  10  grms.  oxalic  acid,  and  add  30  cc.  concen- 
trated sulphuric  acid  through  the  thistle-tube.  Fill 
the  wash-bottle  half  full  of  sodium  hydrate  solu- 
tion. Now  heat  gently  at  first,  afterwards  more 
strongly,  and,  when  air  is  expelled,  collect  gas  by 
displacement  of  water. 

Keaction  :   C2H2O4  =  COa  +  CO  +  H2O. 

The  sulphuric  acid  serves  to  remove  water  from  the 
oxalic  acid.  Why  is  the  wash-bottle  containing 
sodium  hydrate  used? 

Give  physical  properties  of  carbon  monoxide. 
Compare  it  in  all  respects  with  carbon  dioxide.  Ex- 
plain how  the  two  oxides  of  carbon  illustrate  the  law 
of  multiple  proportions. 

References  :  Clk.,  pp.  90-98 ;  Cly.,  pp.  153-156  ;  E., 
pp.  168-179  ;  S.,  pp.  136-145  ;  S.  and  L.,  pp.  176-183  ; 
W.,  pp.  165-178. 


EXERCISE  21. 

FLAMES. 
(a)   The  Nature  of  Flames. 

Heat  a  piece  of  charcoal  till  it  glows.  Here  is 
combustion,  but  no  flame.  Did  you  get  a  flame 
when  glowing  charcoal  was  plunged  into  oxygen, 
or  only  a  more  intense  glowing  ?  Now  light  a  candle. 
Have  you  here  a  flame  ?  After  it  is  burning  well, 
blow  it  out  suddenly,  and  hold  a  lighted  splinter 
a  little  above  the  wick.  Can  you  relight  the  candle 
without  applying  the  light  to  the  wick  ? 

Place  1  grm.  of  stearin  (from  a  candle)  in  a  small 
crucible.  (See  Fig.  20.)  Heat  strongly.  Are  gases 
evolved  ?  Can  you  light  them  above  the  crucible  ? 

Repeat  the  experiment,  using  a  few  drops  of  alcohol. 
Results?  Fill  a  test-tube  one-third  full  of  bits  of 
wood  and  heat.  Are  combustible  gases  given  off? 
Do  you  think  that  any  substance  that  burns  with  a 
flame  will,  on  heating,  give  off  combustible  gases  ? 
If  so,  what  is  a  flame? 

(b)  Kindling-point. 

Do  all  substances  begin  to  burn  at  the  same  tem- 
perature ?  Test  with  the  following  :  1  cc.  of  carbon 
d!sulphide,  in  a  small  beaker  ;  a  match  ;  and  a  candle. 
Warm  a  glass  rod  and  hold  in  the  vapor  of  the  carbon 
disulphide,  then  immediately  touch  each  of  the  other 

58 


FLAMES.  59 

two.  Repeat  the  experiment  with  the  rod  a  little 
hotter  each  time,  till  one  of  the  substances  is  kindled. 
Now  see  which  of  the  remaining  two  you  can  light 
with  a  hot  rod.  Does  each  substance  seem  to  have 
its  own  distinct  kindling-point  ? 

Bring  down  a  piece  of  wire  gauze  on  the  flame  of  a 
burner.  Does  the  flame  pass  through  the  gauze  ? 
Apply  a  light  above  the  gauze.  What  takes  place  ? 
Explain  fully  the  principle  of  the  safety-lamp. 

(c)  Light  of  Flames. 

Could  you  read  well  by  the  light  of  an  alcohol  or  a 
hydrogen-flame  ?  Hold  a  clean  evaporating-dish  in 
burning  alcohol.  Is  any  soot  (carbon)  deposited? 
Try  the  same  experiment  with  a  candle-flame.  To 
what  is  the  light  of  an  ordinary  flame  principally  due  ? 

Alcohol  is  a  little  over  50$  carbon.  Oil  of  turpen- 
tine is  nearly  90$  carbon.  Which  do  you  think  will 
burn  with  the  more  luminous  (and  sooty)  flame? 
Light  a  very  little  of  each,  and  see  if  your  reasoning 
is  correct. 

References :  Clk.,  pp.  84-89  ;  Cly.,  pp.  159-171 ;  R, 
pp.  180-189  ;  S.,  pp.  27-29  ;  S.  and  L.,  pp.  183-193; 
W.,  pp.  53-62. 


EXERCISE  22. 

BROMINE. 

Work  with  bromine  must  be  performed  under  the  hood  or  where 
the  draft  is  good.  Avoid  inhaling  the  fumes. 

(a)  Bromine-vapor. 

Place  in  a  large  test-tube  2  or  3  crystals  of  potassium 
bromide  with  an  equal  quantity  of  manganese  dioxide. 
Add  a  few  drops  of  concentrated  sulphuric  acid  and 
warm.  Note  color  of  vapor.  Will  it  bleach?  Try 
with  moistened  calico.  How  does  the  action  compare 
with  that  of  chlorine? 

(b)  Bromine  (Liquid)  and  Bromine-water. 

Put  a  pulverized  mixture  consisting  of  3  grms.  po- 
tassium bromide  and  an  equal  weight  of  manganese 
dioxide  into  retort  of  apparatus  shown  in  Fig.  18. 
Pour  10  cc.  concentrated  sulphuric  acid  into  50  cc. 
of  water,  and  when  the  liquid  is  cool  introduce  it  by 
means  of  a  funnel  into  the  retort.  Shake  to  be  sure 
that  the  acid  is  in  contact  with  all  parts  of  the  mixture 
and  then  heat  gently.  Put  a  little  water  into  the  test- 
tube  used  as  a  receiver,  and  let  the  end  of  the  retort 
dip  below  the  surface  of  the  water.  This  is  to  prevent 
evaporation.  Now  continue  to  heat  till  brown  fumes 
no  longer  come  off. 

.  The  heavy  brown  liquid  in  the  test-tube  is  bromine. 
Compare  it  with  chlorine,  giving  the  physical  proper- 
ties of  each.  The  reaction  representing  the  liberation 

6u 


BROMINE.  61 

of  bromine  is  exactly  analogous  to  the  reaction  that 
you  learned  in  preparing  chlorine.  Write  the  reaction 
for  bromine. 

How  do  you  account  for  the  color  of  the  water  above 
the  bromine?  Is  bromine  soluble  in  water? 

Bromine  is  very  soluble  in  carbon  disulphide.  To 
a  few  cc.  of  bromine-water  (free  from  liquid  bromine) 
in  a  test-tube  add  1  drop  of  carbon  disulphide,  close  the 
test-tube  with  the  thumb  and  shake  vigorously.  Allow 
to  settle.  Which  now  contains  the  bromine  in  solu- 
tion, the  water  or  the  carbon  disulphide  ?  Note  the 
color  of  each.  Do  you  think  that  you  could  prove  the 
presence  of  bromine  in  solution  by  this  test?  Now 
try  the  same  test  with  a  solution  of  potassium  bro- 
mide. Can  we  use  this  test  for  compounds  containing 
bromine  or  only  for  bromine  itself  (free  bromine)? 

To  a  few  cc.  of  a  dilute  solution  of  potassium 
bromide  add  a  little  chlorine-water.  Does  the  solu- 
tion become  colored  ?  Now  shake  with  a  drop  of  car- 
bon disulphide.  Has  bromine  been  liberated  by  the 
chlorine?  Which  has  the  greater  affinity  for  potas- 
sium, bromine  or  chlorine  ?  Complete  the  reaction  : 
KBr  +  Cl  =  .  .  . 

(c)  Hydrobromic  Acid  and  some  of  its  Salts. 

Put  a  crystal  of  potassium  bromide  in  a  test-tube, 
add  a  little  dilute  sulphuric  acid  and  heat.  Test  the 
escaping  gas  with  litmus  paper.  Write  the  reaction 
representing  the  liberation  of  hydrobromic  acid.  See 
corresponding  reaction  for  hydrochloric  acid. 

In  making  the  following  bromides  we  may  use  either 
hydrobromic  acid  or  a  soluble  bromide. 

AgNO,  +  HBr  =  AgBr  +  HNOS. 
AgNO,  +  KBr  =  AgBr  -}   KNO,. 


62  THE  NON-METALLIC  ELEMENTS. 

Add  a  few  drops  of  potassium  bromide  solution,  in 
separate  tests,  to  solutions  of  silver  nitrate,  mercurous 
nitrate,  and  lead  acetate.  Describe  results  and  write 
reactions. 

(d)  PROBLEMS. 

1.  How  much  bromine  can  be  obtained  from   60 
grms.  potassium  bromide  ? 

2.  How  much  potassium  bromide  must  be  taken  to 
obtain  60  grms.  of  bromine  ? 

3.  How  much  potassium  bisulphate  will  be  formed 
in  problem  2  ? 

References:  Clk.,  p.  128;  Cly.,  p.  75;  K.,  pp.  217- 
220;  S.,  pp.  108-114;  S.  and  L.,  pp.  87-90;  W.,  pp. 
208-211. 


EXERCISE  23. 

IODINE. 

Grind  together  in  a  mortar  2  grms.  of  potassium 
iodide  and  4  grms.  of  manganese  dioxide.  Place  the 
mixture  in  a  beaker  of  300  to  400  cc.  capacity  and  add 
drop  by  drop  about  5  cc.  of  concentrated  sulphuric 
acid.  Select  an  evaporating-dish  whose  diameter  is 
a  little  larger  than  that  of  the  beaker.  Fill  the 
evaporating-dish  three  fourths  full  of  water,  see  that 
the  under  surface  is  perfectly  clean  and  dry,  and  place 
on  the  beaker.  Now  set  beaker  and  contents,  covered 
as  just  directed,  on  a  wire  gauze  supported  by  the 
ring-stand.  Heat  cautiously  and  note  the  color  of 
the  iodine-vapor.  Conduct  the  heating  in  such  a  way 
that  the  iodine-vapor  just  fills  the  beaker.  (Too  rapid 
heating  is  to  be  avoided.  Half  an  hour  will  be  re- 
quired to  obtain  good  results.)  If  the  iodine  collects 
on  the  sides  of  the  beaker,  vaporize .  it  by  cautious 
heating.  Continue  the  heating  till  nearly  all  the 
iodine  has  collected  on  the  cool  surface  of  the  evapora- 
ting-dish. Then  remove  the  dish,  throw  out  the  water 
without  wetting  the  iodine,  and  scrape  the  iodine  off 
the  dish.  Now  refill  the  dish  with  cool  water,  and 
see  if  you  can  sublime  any  more  iodine  against  it.  If 
so,  add  it  to  the  portion  first  obtained. 

The  liberation  of  iodine  is  analogous  to  the  libera- 
tion of  chlorine  or  bromine.  Write  the  reaction  for 

63 


64:  THE  NON-METALLIC  ELEMENTS. 

iodine.  Describe  in  detail  everything  that  you  have 
noticed  in  connection  with  the  preparation  of  iodine. 

The  most  delicate  test  for  iodine  is  a  solution  of 
starch  paste.  Prepare  this  as  follows:  To  1  grm. 
starch  add  10  cc.  water,  mix  well  and  pour  into  200  cc. 
boiling  water.  Stir  well.  Allow  to  cool  and  settle, 
and  pour  off  the  clear  liquid  for  use  when  required. 
When  the  solution  is  cooling  test  the  solubility  of 
iodine  in  the  following  liquids  :  water,  alcohol,  carbon 
disulphide,  and  a  solution  of  potassium  iodide.  Use 
a  test-tube  full  half  of  (hot)  water  and  4  or  5  drops  of 
each  of  the  other  solvents.  In  which  do  you  think 
that  iodine  is  the  most  soluble  ? 

Now  make  the  "  starch  test "  as  follows :  Add  a  few 
cc.  of  the  starch  solution  to  100  cc.  of  water  and  then 
add  the  water  solution  of  iodine  till  a  deep  blue  ap- 
pears. If  you  do  not  succeed  in  this  way,  dilute  the 
solution  of  iodine  in  potassium  iodide  with  a  large 
excess  of  water  and  add  a  drop  of  this  dilute  solution. 
The  success  of  the  experiment  depends  on  the  relative 
amounts  of  starch,  water,  and  iodine. 

To  another  portion  of  the  water  solution  or  to  a  very 
dilute  potassium  iodide  solution  of  iodine  add  a  drop 
of  carbon  disulphide  and  shake  well.  What  takes 
place  ?  Compare  the  deportment  of  bromine  with  this 
reagent. 

Dissolve  a  minute  amount  of  potassium  iodide  in  a 
test-tube  half  full  of  water.  Does  the  solution  react 
with  starch  ?  Now  add  a  drop  or  two  of  chlorine-water 
and  note  result.  Shake  a  little  of  potassium  iodide 
solution  with  a  drop  of  carbon  disulphide.  Does  any 
change  of  color  occur  ?  Now  add  a  drop  or  two  of 
chlorine-water  and  shake  again.  Result?  Explain 
fully  the  principles  involved. 


IODINE.  65 


Treat  silver  nitrate,  mercurous  nitrate,  and 
nitrate  with  a  solution  of  potassium  iodide.  Describe 
results  and  write  reactions.  Compare  with  the  action 
of  potassium  bromide. 

PKOBLEMS. 

(1)  How  much  potassium  iodide  must  you  take  to 
obtain  100  grms.  of  iodine  ? 

(2)  How  much  manganese  dioxide  would  be  required 
in  problem  (1)  ? 

References:  Clk.,  pp.  129-131;  Cly.,  p.  75;  R,  pp. 
220-222;  S.f  pp.  115-118;  S.  and  L.,  pp.  90-93;  W., 
pp.  211-215. 


EXERCISE  24. 
FLUORINE. 

Give  a  brief  description  of  the  properties  of  fluorine 
using  your  text-book  or  lecture-notes  as  your  source 
of  information.  Why  do  we  not  prepare  fluorine  for 
study  in  the  laboratory  ? 

Hydrofluoric  Acid. 

This  compound  attacks  glass,  hence  we  cannot  well 
study  it  very  fully.  It  is  liberated  from  its  salts  by 
the  action  of  sulphuric  acid.  Write  the  reaction  that 
takes  place  between  calcium  fluoride  (CaF2)  and  sul- 
phuric acid.  The  action  of  hydrofluoric  acid  on  glass 
may  be  shown  in  the  following  way :  Cover  a  piece  of 
window-glass  with  a  coating  of  beeswax  or  paraffine 
somewhat  thicker  than  the  paper  of  this  book.  This 
is  best  done  by  carefully  warming  the  glass  and  rub- 
bing the  wax  over  its  surface.  The  coating  should  be 
on  both  sides  of  the  glass  and  as  uniform  as  possible. 
Engrave  some  design  in  the  wax  by  means  of  a  pointed 
instrument.  Be  sure  that  the  point  of  the  instrument 
entirely  removes  the  wax  and  that  the  lines  are  not  too 
fine.  Put  3  grms.  calcium  fluoride  in  a  leaden  dish 
and  add  enough  cone,  sulphuric  acid  to  form  a  thin 
paste.  Cover  the  dish  with  the  plate  that  you  have 
prepared  with  the  engraved  side  down.  Avoid  inhal- 
ing the  fumes.  Allow  the  dish  thus  covered  to  stand 
for  several  hours,  or  till  your  next  laboratory  period, 

66 


FLUORINE.  67 

under  the  hood.  Next  remove  the  plate  and  at  once 
wash  the  contents  of  the  dish  into  the  waste-jar.  It  is 
sometimes  troublesome  to  remove  the  wax.  This  can 
be  done  without  cracking  the  glass  by  putting  in  water, 
heating  to  boiling,  continuing  the  boiling  for  a  few 
minutes,  then  cooling  till  the  hand  can  be  placed  in 
the  water  without  scalding.  The  plate  may  now  be 
removed  and  rubbed  with  a  cloth  moistened  with  alco- 
hol. Show  the  etched  plate  to  your  instructor  for 
approval.  The  reaction  between  the  acid  and  the 
glass  is  as  follows  : 

SiO2  +  4HF  =  SiF4  +  2H2O. 

We  have,  for  convenience,  studied  the  halogens 
(fluorine,  chlorine,  bromine  and  iodine)  in  an  illogical 
order.  Now  make  a  thorough  review  of  these  com- 
pounds. Show  in  what  respects  they  resemble  each 
other.  Make  a  list  of  their  atomic  weights  and  show 
that  their  properties  are  related  to  their  atomic 
weights. 

References:  Clk.,  pp.  111-113;  Cly.,  pp.  75,  76  ;  K, 
pp.  223-225 ;  S.,  pp.  122-124 ;  S.  and  L.,  pp.  77-79, 
94-95  ;  W.,  p.  215. 


EXERCISE  25. 

SULPHUR. 

(a)  Rhombic  Sulphur. 

Dissolve  in  a  small  beaker  1  grm.  of  roll  sulphur  in 
carbon  disulphide,  using  as  small  a  quantity  as  will 
effect  solution.  Set  the  beaker  under  the  hood,  away 
from  flames,  and  allow  the  solvent  to  evaporate.  Note 
the  form  of  the  crystals. 

(b)  Monodinic  Sulphur. 

Fill  a  porcelain  crucible  with  roll  sulphur  and  melt 
at  a  low  temperature.  Add  more  sulphur  as  it  melts 
down,  continuing  the  heating  at  a  low  temperature,  till 
the  crucible  is  full  of  the  molten  sulphur.  Now  allow 
to  cool  until  a  crystalline  crust  begins  to  form  on  the 
surface.  Make  an  opening  and  pour  out  the  remain- 
ing molten  sulphur.  Note  the  kinds  of  crystals  in  the 
cavity.  Allow  them  to  stand  several  days.  Do  you 
notice  any  change  in  general  appearance  or  form  ? 

(Write  out  a  brief  description  of  each  of  the  six 
systems  of  crystals.  See  text  or  reference-books.) 

(c)  Plastic  Sulphur. 

Put  about  5  grms.  sulphur  in  a  dry  test-tube,  held 
with  a  clamp,  and  heat  gradually.  Note  that  you  first 
obtain  a  thin  amber-colored  liquid  which  gradually 
becomes  dark  and  viscous  as  the  temperature  rises. 


SULPHUR.  69 

Tliis  soon  becomes  tliinuer,  and  finally  the  tube  is 
filled  with  sulphur-vapor.  Pour  the  molten  sulphur 
into  a  beaker  containing  water.  Examine  and  describe 
the  sulphur  in  the  beaker.  Allow  it  to  stand  till  your 
next  laboratory  period.  Is  it  still  plastic  ? 

Now  compare  the  three  allotropic  forms  of  sulphur. 
Which  form  is  the  most  stable?  What  substance 
have  you  studied  all  of  whose  allotropic  forms  are 
stable  ? 

Where  is  the  greater  part  of  the  sulphur  of  com- 
merce obtained  ?  How  is  it  freed  from  impurities  ? 

References  :  Clk.,  pp.  132-137  ;  Cly.,  pp.  101-103 ; 
EM  pp.  226-230  ;  S ,  pp.  157-160  ;  S.  and  L.,  pp.  99- 
105  ;  W.,  pp.  238-243,  108. 


EXERCISE  26. 

SULPHIDES. 
(a)  Hydrogen  Sulphide. 

All  work  with  hydrogen  sulphide  must  be  done  under  the  hood  or 
where  the  draft  is  good.  Put  all  residues  in  waste-jar  under  the 
hood  or  out  of  doors.  Avoid  inhaling  the  gas. 

Set  up  apparatus  exactly  as  in  Fig.  13,  except  the 
delivery-tube.  Put  20  grms.  ferrous  sulpliide  in  the 
generator  and  50  cc.  of  water  in  the  small  bottle. 
Attach  to  this  bottle  a  delivery-tube  such  as  you  have 
used  in  collecting  gases  by  displacement  of  air. 
When  the  apparatus  is  in  order,  pour  dilute  sulphuric 
acid  into  the  generator  through  the  thistle-tube.  After 
all  air  is  expelled,  collect  a  bottle  of  the  washed  gas 
by  displacement  of  air.  (Hydrogen  sulphide  is  a 
little  heavier  than  air.)  Will  it  burn  ?  WTill  it  sup- 
port combustion  ?  Has  it  any  color  or  odor  ?  Test 
its  solubility  in  the  water  in  the  following  way :  Pass 
a  few  bubbles  of  the  gas  into  water  in  a  test-tube.  Is 
the  gas  entirely  absorbed  ?  Is  enough  absorbed  to 
impart  its  odor  to  the  water?  Complete  the  reac- 
tion showing  the  formation  of  hydrogen  sulphide  : 

FeS  +  H3S04 

(b)  Formation  of  Sulphides  by  Direct  Combination. 

Pass  hydrogen  sulphide  into  a  solution  of  copper 
sulphate  (CuSO4).  Write  the  reaction.  Filter  off 

70 


SULPHIDES.  71 

the  precipitated  copper  sulphide.  See  note  on  filtra- 
tion, Exercise  9.  Wash  the  precipitate  by  filling  the 
cone  formed  by  the  filter-paper  full  of  distilled  water. 
The  water,  as  it  soaks  through,  dissolves  out  foreign 
matter  held  by  the  precipitate,  thus  "washing "  it. 
Wash  thoroughly.  Is  the  precipitate  soluble  in 
dilute  sulphuric  acid  ?  If  it  were,  could  it  be  formed 
by  the  reaction  that  you  have  written  ? 

Using  a  solution  of  lead  nitrate,  precipitate  lead 
sulphide.  Filter  and  wash  the  precipitate.  Test  its 
solubility  in  dilute  nitric  acid. 

Pass  hydrogen  sulphide  into  a  solution  of  ferrous 
(iron)  sulphate.  Do  you  notice  any  precipitate  or, 
at  most,  anything  more  than  a  slight  precipitate  ? 
Now  add  ammonium  hydrate  and  continue  to  pass  in 
the  gas.  Filter  and  wash  the  precipitate.  Reaction  : 

FeS04  +  H2S  +  2NH4OH  =  FeS  +  (NH4)2SO4+  2H2O. 

Test  the  solubility  of  the  washed  precipitate  in  dilute 
sulphuric  acid.  What  odor  is  given  off  ?  Reaction  ? 
Why  is  ferrous  sulphide  not  precipitated  without 
the  ammonium  hydrate  according  to  the  reaction  : 
FeS04  +  H2S  =  FeS  +  H2S04  ? 

Make  a  little  ferrous  sulphide  as  in  Exercise  4, 
paragraph  (/).  Test  it  with  dilute  sulphuric  acid.  Is 
it  the  same  substance  that  you  have  just  studied? 
Why  do  you  think  so  ? 

(c)   Test  for  Soluble  Sulphides. 

Put  a  little  sodium  sulphide  on  a  clean  silver  coin. 
Moisten  with  a  drop  of  water  and  crush  the  sulphide. 
Allow  to  stand  for  some  time  and  then  wash.  Note 
the  black  spot  (silver  sulphide)  on  the  coin.  Since 
sulphur  or  any  of  its  compounds  may  be  converted 


72  THE  NON-METALLIC  ELEMENTS. 

into  sodium  sulphide  by  fusing  with  sodium  car- 
bonate on  charcoal,  the  above  test  is  used  to  detect 
sulphur  in  any  of  its  forms.  Fuse  a  little  sulphur 
mixed  with  an  equal  quantity  of  sodium  carbonate 
on  charcoal.  Cut  out  the  fused  mass  and  test  on 
silver  as  above. 

(d)  Test  for  Hydrogen  Sulphide. 

Moisten  a  piece  of  filter-paper  with  a  drop  of  lead 
acetate  solution.  Hydrogen  sulphide  turns  the  paper 
black.  Explain. 

Has  hydrogen  sulphide  acid,  neutral,  or  basic 
properties  ? 

References:  Clk.,  pp.  136,  137;  Cly.,  pp.  104,105; 
K.,  pp.  231-234 ;  S.,  pp.  160-163  ;  S.  and  L.,  pp.  106- 
109  ;  W.,  pp.  243-246. 


EXERCISE  27. 

SULPHUR  COMPOUNDS  CONTAINING  OXYGEN. 

(a)  Sulphur  Dioxide. 

Burn  a  little  sulphur  (deflagrating-spoon)  in  a  wide- 
mouthed  bottle.  Cautiously  note  the  odor.  Write 
the  reaction.  Add  a  little  water  to  the  bottle  and 
shake  well.  Test  the  liquid  with  litmus  paper. 

Set  up  apparatus  as  shown  in  Fig.  15.  Put  10  grms. 
of  copper-foil  or  copper  turnings  in  the  flask  and  add 
about  25  cc.  concentrated  sulphuric  acid  through  the 
thistle-tube.  Heat  gradually,  increasing  the  tempera- 
ture, till  a  gas  comes  off,  then  moderate  the  heating. 
Catch  a  bottle  of  the  gas  by  displacement  of  air.  Is 
it  the  same  compound  as  you  prepared  by  burning 
sulphur  ?  Test  the  bleaching  action  of  sulphur 
dioxide  on  a  piece  of  red  calico  on  a  red  flower,  if  you 
can  procure  one.  Compare  with  the  action  of  chlorine. 
Which  bleaches  the  more  vigorously  ? 

Dissolve  1  grm.  of  sodium  hydrate  in  10  cc.  of  dis- 
tilled water,  and  pass  sulphur  dioxide  into  the  solution 
till  the  reaction  is  neutral  to  litmus.  You  now  have  a 
solution  of  sodium  sulphite,  NaaSO8.  Write  the  reac- 
tion. To  a  small  portion  of  the  solution  add  HC1. 
What  gas  is  given  off?  Write  the  reaction. 

To  another  portion  add  barium  chloride  solution. 
Barium  sulphite  (BaSO3)  is  formed'.  Eeaction?  Is 
barium  sulphite  soluble  in  dilute  hydrochloric  acid  ? 
(A  little  insoluble  barium  sulphate  may  be  present.) 

73 


74  THE  NON-METALLIC  ELEMENTS. 

To  another  portion  of  the  sodium  sulphite  solution 
add  nitric  acid  and  boil.  Now  add  barium  chloride 
solution  and  treat  as  above.  Is  the  precipitate  solu- 
ble in  hydrochloric  acid  ? 

Nitric  acid  is  a  good  oxidizing  agent.  You  now  have 
barium  sulphate,  which  is  insoluble  in  acids. 

(b)  Sulphuric  Acid. 

Describe  the  process  of  making  sulphuric  acid. 
Give  some  of  the  uses  of  this  acid. 

To  1  cc.  water  in  a  test-tube  add  1  cc.  concentrated 
sulphuric  acid  and  note  any  change  in  temperature. 
Write  with  this  acid  on  a  piece  of  paper  by  means  of 
a  splinter.  Warm  for  a  few  minutes  and  note  result. 

Put  £  grm.  sugar  in  a  test-tube,  add  concentrated 
sulphuric  acid  and  warm.  What  do  you  notice  ? 
What  do  you  conclude  from  these  experiments  con- 
cerning the  affinity  of  sulphuric  acid  for  water  ? 

To  a  drop  of  dilute  sulphuric  acid  add  a  little 
barium  chloride  solution.  Reaction  ?  Try  to  dissolve 
the  precipitate  in  water.  In  dilute  acids.  Results? 
Try  the  same  experiments,  using  calcium  chloride 
instead  of  barium  chloride. 

References:  Clk.,  pp.  138-149;  Cly.,  pp.  106-111; 
E.,  pp.  235-241 ;  S.,  pp.  164-176 ;  S.  and  L.,  pp.  110- 
120 ;  W.,  pp.  124-132,  247,  248. 


EXERCISE  28. 

PHOSPHORUS. 

For  precautions  in  using  phosphorus  see  Exercise  15. 
(a)   Ydlow  Phosphorus. 

Put  some  water  in  an  evaporating-dish  and  ask  your 
instructor  to  place  in  it  three  pieces  of  phosphorus 
about  the  size  of  grains  of  wheat.  Remove  one  with 
the  pincers,  dry  by  bringing  in  contact  with  filter-paper, 
and  place  in  a  clean  dry  pprcelain  crucible.  Note 
that  white  fumes  are  given  off.  The  phosphorus  glows 
in  the  dark.  What  does  the  word  phosphorus  signify  ? 
Let  the  crucible  containing  the  phosphorus  float  on 
water  in  a  beaker.  Place  the  beaker  on  the  wire  gauze 
and  heat  gently.  Does  the  phosphorus  melt?  Does 
it  burn  ?  Note  the  temperature  of  the  water  with 
your  hand.  The  white  fumes  are  phosphorus  pentox- 
ide  (P2O6).  Write  the  reaction  representing  the  burn- 
ing of  phosphorus. 

Perform  the  following  experiment  exactly  as  di- 
rected. In  a  dry  test-tube  held  with  a  clamp,  place  1 
cc.  carbon  disulphide.  (Cork  and  remove  from  your 
working  place  any  carbon  disulphide  that  you  may 
have  aside  from  the  amount  just  given.)  Drop  into 
the  tube  one  piece  of  phosphorus.  Does  it  dissolve  in 
the  carbon  disulphide  ?  Cover  a  beaker  with  a  round 
filter  a  little  larger  in  diameter  than  the  beaker. 
Now,  holding  the  tube  with  the  clamp,  pour  the  solu- 

75 


76  TEE  NON-METALLIC  ELEMENTS. 

tion  on  the  filter-paper.  Stand  a  few  feet  distant  and 
note  what  takes  place  after  the  carbon  disulphide  has 
evaporated. 

Put  a  few  crystals  of  iodine  in  a  dry  test-tube  and 
drop  on  them  a  piece  of  dry  phosphorus.  The  phos- 
phorus unites  with  the  iodine  forming  PI2.  Write  the 
reaction. 

What  do  you  conclude  from  these  experiments  about 
the  chemical  activity  of  yellow  phosphorus  ?  Explain 
the  use  of  phosphorus  in  matches. 

(b)  Red  Phosphorus. 

(This  kind  of  phosphorus  may  be  safely  handled 
without  special  precautions.)  Is  red  phosphorus 
soluble  in  carbon  disulphide  ?  Does  it  ignite  at  a  low 
temperature  ?  Try  its  action  on  iodine. 

Put  i  grm.  of  red  phosphorus  on  the  iron  base  of 
your  ring-stand.  Ignite  under  the  hood.  Do  you 
think  that  the  product  of  combustion  is  the  same  as 
when  yellow  phosphorus  burns  ?  Why  ?  Compare 
the  allotropic  forms  of  phosphorus. 

(c)  Phosphine. 

Heat  a  little  calcium  hypophosphite  in  a  test-tube. 
Note  the  inflammability  of  the  impure  phosphine  (PH9) 
formed. 

Complete  the  reaction :  2PH8  -f-  4Oa  =  .  .  . 

(d)  Phosphoric  Acid. 

Note. — The  acids  containing  phosphorus  are  very  numerous.  We 
will  here  study  only  the  orthophosphoric  acid.  Commercial  phos- 
phoric acid  usually  consists  of  metaphosphoric  acid.  This  as  well  as 
pyrophosphoric  acid,  which  is  sometimes  present,  is  converted  into 
the  ortho  acid  by  boiling  for  some  time  with  excess  of  water. 


PHOSPHORUS.  77 

Neutralize  a  few  cc.  of  a  solution  of  orthophosplioric 
acid  with  ammonium  hydrate.  Be  sure  that  the  solu- 
tion is  exactly  neutral  to  litmus.  Add  silver  nitrate 
solution,  describe  the  precipitate  and  write  the  reac- 
tion. 

To  1  cc.  of  phosphoric  acid  solution  add  a  few  drops 
of  a  solution  of  ammonium  molybdate.  In  very  dilute 
solutions  the  precipitate  appears  after  some  time  has 
elapsed.  Describe  the  precipitate. 

Repeat  the  experiment  just  given,  using  disodium 
phosphate  instead  of  phosphoric  acid.  Result  ? 

Test  for  phosphates  in  bone  ash  as  follows :  Digest 
1  grm.  of  bone-ash  with  dilute  sulphuric  acid  by  gently 
heating  (not  boiling)  for  about  10  minutes.  Filter  and 
add  ammonium  molybdate  solution  to  the  clear  filtrate. 
Do  you  obtain  a  precipitate  ?  If  so,  describe  it. 

Try  the  same  experiment,  using  coal-ash  instead  of 
bone-ash.  Have  you  any  evidence  that  coal-ash  con- 
tains phosphates  ? 

What  use  is  made  of  the  natural  phosphates? 

References :  Clk.,  pp.  151-158 ;  Cly.,  pp.  130-133  ; 
E,  pp.  241-248 ;  S.,  pp.  193-196 ;  S.  and  L.,  pp.  139-147 ; 
W.,  pp.  249-258. 


EXERCISE  29 

ARSENIC. 

Note. — Remember  the  poisonous  properties  of  arsenic  compounds. 

Examine  a  piece  of  "  metallic  "  arsenic  about  the 
size  of  a  grain  of  wheat.  Heat  it  on  charcoal  before 
the  blowpipe.  Note  that  a  white  deposit  of  arsenic 
trioxide  appears  on  the  charcoal.  Write  the  reaction. 

Make  a  small  ignition-tube  according  to  directions 
given  in  Exercise  6.  Place  in  it  a  small  amount  (equal 
in  volume  to  a  coarsely  broken  half  pea)  of  arsenic 
trioxide,  "  white  arsenic."  Dry  a  piece  of  charcoal  by 
heating  over  the  flame  of  a  burner.  Cool  and  cut  it 
into  the  form  of  a  cylinder  2  cm.  (f  inch)  long,  having 
just  the  diameter  of  the  bore  of  the  tube.  Push  this 
charcoal  plug  into  the  ignition-tube  to  within  about 
13  mm.  (-J-  inch)  of  the  arsenic  trioxide.  Heat  the  char- 
coal as  hot  as  possible,  allowing  the  end  of  the  tube 
containing  the  oxide  to  extend  out  of  the  flame.  When 
the  glass  around  the  charcoal  is  nearly  red-hot,  hold 
the  tube  in  a  more  nearly  vertical  position,  so  that  the 
flame  may  strike  both  the  charcoal  and  the  white 
arsenic  at  the  same  time.  What  forms  on  the  cool 
surface  above  the  charcoal  ?  What  reaction  has  taken 
place  between  the  vapor  of  arsenic  trioxide  and  the 
carbon  ?  When  the  tube  is  cool  cut  off  the  lower  end 
and  remove  the  carbon.  Now  hold  the  tube  at  an 
angle  of  45°  and  heat  again.  What  takes  place  ?  Ex- 
plain fully. 

78 


ARSENIC.  79 

(a)  Arsine  (Asffs). 

This  compound  is  a  deadly  poison,  hence  it  should 
not  be  prepared  by  any  except  experienced  chemists. 
Study  its  properties  in  your  text-book  and  describe  it 
fully. 

(b)  Comparison  of  Arsine  with  Stibine. 

Perform  the  following  experiment  under  the  hood. 

Stibine  or  hydrogen  antimonide  (SbH3)  may  be  made 
as  follows  :  Set  up  apparatus  of  the  same  general 
character  as  shown  in  Fig.  13.  See  that  the  small 
bottle  is  dry,  and  place  in  it  granulated  calcium  chlo- 
ride, in  sufficient  quantity  to  cover  the  bottom  with  a 
layer  about  an  inch  deep.  The  tube  from  the  gen- 
erator should  reach  almost  to  the  bottom  of  the  bot- 
tle. The  calcium  chloride  serves  to  dry  the  gas.  At- 
tach at  B  a  tube  drawn  out  to  a  rather  fine  bore.  Now 
generate  hydrogen  as  directed  in  Exercise  8,  and  after 
all  air  is  expelled  light  the  gas.  Hold  in  the  flame  a 
cool  porcelain  dish.  Is  a  black  spot  produced  ?  If 
so,  arsenic  or  antimony  may  be  present  in  the  reagents. 
Now  pour  through  the  thistle-tube  a  few  drops  of  a 
solution  of  any  antimony  compound  (as  tartar  emetic). 
Does  the  hydrogen -flame  change  color?  Hold  the 
dish  in  the  flame.  Is  a  spot  deposited  ?  How  could 
you  distinguish  it  from  an  arsenic  spot  ?  (Consult 
text). 

(e)  Show  some  of  the  points  of  similarity  between 
arsenic,  antimony,  and  bismuth. 

References:  Clk.,  pp.  159-162,  247-252;  Cly.,  pp. 
134-137,  231 ;  E.,  pp.  249-253 ;  S.,  *pp.  242-250,  255- 
258  ;  S,  and  L.,  pp.  149-160  ;  W.,  pp.  321-331,  336-339. 


EXERCISE  30. 
SILICON  ;  BORON  ;  REVIEW  OF  NON-METALS. 

(a)  Silicon. 

How  is  silicon  prepared  ?  Give  its  chemical  and 
physical  properties.  (Consult  text.) 

To  a  solution  of  sodium  silicate  "  water-glass  "  add 
dilute  hydrochloric  acid  to  distinctly  acid  reaction. 
Evaporate  very  cautiously  to  dryness  in  a  small  evap- 
orating-dish  on  the  wire  gauze.  The  residue  is  silicon 
dioxide  (SiOa)  mixed  with  common  salt.  Is  it  (SiO2) 
soluble  in  water  ?  in  acids  ?  Silicon  dioxide  (silica) 
is  the  anhydride  of  the  silicic  acids.  One  of  these  has 
the  symbol  HaSiO9.  Compare  its  structure  with  that 
of  carbonic  acid. 

What  is  quartz?  Quartz  sand?  Glass?  How  is 
glass  made  ? 

(b)  Boron. 

How  is  boron  prepared  ?  Give  its  physical  and 
chemical  properties.  (Consult  text.) 

Dissolve  lOgrms.of  borax  (sodium  biborate,  Na2B4O7) 
in  25  cc.  boiling  water.  To  the  hot  solution  add  6  cc. 
concentrated  hydrochloric  acid.  On  cooling  crystals 
of  boric  acid  (H3BO8)  separate  out.  "Write  the  re- 
action. 

Filter  off  the  boric  acid  from  the  mother  liquor,  and 
dissolve  a  few  crystals  in  2  cc.  of  alcohol.  Set  fire  to 
the  solution  in  a  small  evaporating-dish.  Note  the 
color  of  the  flame. 

80 


SILICON;  BORON;  REVIEW  OF  NON-METAL8.       81 

(c)  Revieiu. 

Explain  the  difference  between  metals  and  non- 
metals.  Is  it  possible  to  make  a  sharp  distinction  in 
all  cases  ? 

Make  a  list  of  all  the  non-metallic  elements  that  you 
have,  studied,  giving  the  atomic  weights.  Also  make 
a  list  of  the  compounds  that  you  have  studied,  giving 
formulas  and  molecular  weights.  (This  list  is  not  to 
include  complicated  compounds,  as  sugar,  starch, 
starch  iodide,  etc.) 

References:  Clk.,  pp.  163-171;  Cly.,  pp.  137,  138, 
143-147 ;  R,  pp.  255-260 ;  S.,  pp.  184-192 ;  S.  and  L., 
pp.  161-165;  W.,  pp.  259-275. 


THE  MOKE  IMPORTANT  METALS. 


EXERCISE  31. 

THE  ALKALI  METALS. 

Make  a  list  of  the  metals  of  this  group,  arranged 
in  the  order  of  their  atomic  weights. 

(a)  Sodium. 

Put  a  few  cc.  of  kerosene  in  a  perfectly  dry  dish, 
and  ask  your  instructor  to  place  in  it  a  piece  of  sodium 
as  large  as  a  small  pea.  Examine  the  metal.  (Handle 
alkali  metals  with  pincers.)  Describe  its  physical 
properties.  Cut  off  a  little,  free  from  kerosene  by 
pressing  between  filter-paper,  and  expose  to  the  action 
of  the  air.  After  twenty  minutes  examine  the  piece 
What  do  you  notice  ?  Why  is  sodium  kept  under 
kerosene  ? 

Pour  into  a  small  evaporating-dish  about  10  cc.  of 
distilled  water.  Now  drop  in  about  half  the  sodium 
that  you  have  and  cover  immediatety  with  a  glass 
plate.  (This  is  to  protect  your  eyes  in  case  there 
should  be  a  slight  explosion  at  the  end  of  the  reac- 
tion.) What  do  you  observe?  Heat  the  solution 
thus  obtained  nearly  to  boiling  and  add  the  rest  of 
the  sodium.  What  takes  place?  To  what  is  the 
flame  due  ?  To  what  is  the  color  of  the  flame  due  ? 

Test  the  solution,  obtained  by  dissolving  the  two 
portions  of  sodium,  with  red  litmus"  paper.  Now  add 
hydrochloric  acid  till  the  solution  is  exactly  neutral. 
Evaporate  to  dryness  and  taste  a  little  of  the  residue. 

85 


86       THE  MORE  IMPORTANT  METALS. 

What  is  it?     Write  the.  reactions,  showing  how  you 
have  made  salt  from  sodium. 

(b)  Potassium. 

Ask  your  instructor  for  a  piece  of  potassium  about 
the  size  of  a  grain  of  barley.  Keep  under  kerosene 
till  you  are  ready  to  use  it.  Examine  its  physical 
properties.  Now  drop  it  on  cold  water,  covering  the 
dish  as  in  the  case  of  sodium.  What  do  you  notice  ? 
Which  do  you  regard  as  the  most  active  chemically, 
sodium  or  potassium  ?  Which  has  the  greater  atomic 
weight?  Which  would  you  expect  to  find  the  more 
active  chemically,  lithium  or  caesium  ?  Why  ? 

(c)  Solubility  of  the  Salts  of  the  Alkali  Metals. 

The  following  may  be  taken  as  representative  com- 
pounds :  sodium  sulphate,  sodium  carbonate,  sodium 
phosphate,  potassium  nitrate,  potassium  chloride, 
potassium  bichromate.  Take  six  perfectly  clean  and 
dry  test-tubes  and  place  in  each  as  much  of  one  of  the 
above-mentioned  salts  as  will  stand  on  the  point  of  a 
knife-blade.  Add  to  each  tube  a  little  water,  and 
warm.  Do  you  find  them  all  soluble  ?  What  do  you 
conclude  in  regard  to  the  solubility  of  most  of  the 
alkali  compounds  ? 

(d)   Flame  Reactions. 

Procure  from  your  instructor  a  piece  of  platinum 
wire  about  2J  inches  long.  Clean  it  before  each  test, 
using  a  clean  cloth  moistened  with  distilled  water. 

Place  one  dror>  of  lithium  chloride  solution  in  a 
clean  dish.  Moisten  the  wire  in  this  solution  and 
hold  in  the  colorless  flame  of  the  burner.  Note  color 


THE  ALKALI  METALS.  87 

of  flame.  Try  the  same  experiment  with  potassium 
chloride ;  with  sodium  chloride ;  with  any  sodium 
compound. 

Name  some  of  the  salts  of  sodium  and  of  potassium 
that  are  of  commercial  importance. 

References :  Clk.,  pp:  183-192 ;  Cly.,  pp.  216-218  ; 
K,  pp.  283-302 ;  S.,  pp.  320-336 ;  S.  and  L.,  pp.  288- 
315;  W,pp.  280-287. 


EXERCISE  32. 

COMPOUNDS  OF  THE  ALKALINE  EARTHS  (CALCIUM,  STRON- 
TIUM, AND  BARIUM). 

(a)   Calcium  Compounds. 

To  2  grms.  of  precipitated  chalk  (calcium  carbonate, 
CaCO,)  add  dilute  hydrochloric  acid,  drop  by  drop, 
with  constant  stirring,  till  solution  is  just  effected. 
Now  add  a  little  more  chalk  to  neutralize  any  excess 
of  acid.  Heat  and  stir  well  in  order  that  all  of  the  acid 
may  come  in  contact  with  chalk.  Add  a  little  water 
to  replace  what  has  evaporated,  and  filter  from  the 
undissolved  portion.  Complete  the  reaction  : 

CaC03  +  2HC1  =  CaCl,  +  .  .  . 

Test  the  flame  reaction  of  the  solution  of  calcium 
chloride  just  prepared.  To  a  few  drops  of  the  calcium 
chloride  solution  add  an  equal  volume  of  sodium  car- 
bonate solution.  The  precipitate  is  calcium  carbon- 
ate. Write  the  reaction.  Try  the  action  of  ammonium 
carbonate.  Reaction  ?  To  the  rest  of  the  solution  of 
calcium  chloride  add  sodium  hydrate  solution.  Cal- 
cium hydrate  is  precipitated.  Write  the  reaction. 

Fill  a  large  test-tube  half  full  of  a  clear  solution  of 
calcium  hydrate  (lime-water).  Generate  carbon  diox- 
ide by  the  action  of  hydrochloric  acid  on  marble,  using 
the  apparatus  shown  in  Fig.  13.  The  gas  is  to  be 
washed  with  water  in  the  small  bottle  in  order  to  free 
it  from  traces  of  hydrochloric  acid.  The  gas  is  now 


COMPOUNDS  OF  THE  ALKALINE  EARTHS.         89 

passed  into  the  lime-water  till  the  precipitate  which 
forms  at  first  is  for  the  most  part  redissolved.  Filter 
the  solution  into  a  clean  beaker  and  boil  for  a  few 
minutes.  What  do  you  notice  ?  Is  this  deposit  cal- 
cium carbonate  ?  Why  do  you  think  so  ?  We  will 
now  study  the  reactions  involved  in  the  entire  process. 
You  have  already  learned  that  calcium  carbonate  is 
formed  by  the  action  of  carbon  dioxide  on  lime-water. 
The  next  step  is  the  solution  of  calcium  carbonate 
according  to  the  reaction  : 

CaC03  +  C02  +  HaO  =  CaH3(CO,),. 

This  compound  (acid  calcium  carbonate)  remains  in 
solution  till  heated,  when  it  breaks  up  according  to  a 
reaction  that  is  just  the  reverse  of  the  one  last  given. 
Write  this  reaction.  Explain  how  water  containing 
carbon  dioxide  dissolves  calcium  carbonate  from  the 
soil  and  rocks,  becomes  hard,  and  leaves  a  deposit  of 
"  lime  "  in  steam-boilers  and  tea-kettles. 

(b)  Strontium  Compounds. 

Test  the  flame  reaction  of  strontium  chloride. 

To  a  few  drops  of  strontium  chloride  solution  add 
the  same  volume  of  sodium  carbonate  solution.  Com- 
plete the  reaction:  SrClt  +  Na,CO3  =  .  .  . 

To  another  portion  of  the  solution  add  a  little  dilute 
sulphuric  acid.  Complete  the  reaction  : 

SrCla  +  .  ..  =  SrS04+... 

To  a  third  portion  add  sodium  Irydrate  solution. 
Strontium  hydrate  Sr(OH)2  is  precipitated.  Write  the 
reaction. 


90  THE  MORE  IMPORTANT  METALS. 

(c)  Barium  Compounds. 

Perform  the  same  experiments  with  barium  chloride 
that  you  did  with  strontium  chloride.  Describe  results 
and  write  reactions.  (The  reactions  are  analogous.) 
Ba  is  substituted  for  Sr.) 

The  formation  of  a  precipitate  indicates  the  forma- 
tion of  an  insoluble  or  a  difficultly  soluble  compound. 
What,  then,  do  you  conclude  as  to  the  solubility  of 
most  of  the  compounds  of  the  alkaline  earths? 

References:  Clk.,  pp.  205-212;  Cly.,  pp.  220,  221; 
R,  pp.  303-318 ;  S.,  pp.  308-316 ;  S.  and  L.,  pp.  315- 
325 ;  W.,  pp.  288-293,  143-147. 


EXERCISE  33. 

MAGNESIUM,  ZINC,  CADMIUM,  AND  MERCURY. 

In  eacli  of  the  groups  of  metals  that  we  have  studied  we  have 
found  a  striking  similarity  of  properties.  The  grouping  of  the  rest 
of  the  metals  is  more  or  less  arbitrary.  Thus  the  metals  considered 
in  this  exercise  do  not  resemble  each  other  in  so  marked  a  degree  as 
do  the  alkaline  earths. 

(a)  Magnesium. 

Describe  the  metal.  Treat  a  little  of  the  metal  (a 
piece  of  magnesium  ribbon  6  mm.  long)  with  dilute  hy- 
drochloric acid.  Try  the  same  experiment  with  dilute 
sulphuric  acid.  Magnesium  chloride  (MgCl,)  and 
magnesium  sulphate  (MgSO4)  are  formed  respectively. 
Write  the  reactions. 

Hold  with  the  pincers  a  piece  of  magnesium 
ribbon  about  25  mm.  (1  inch)  long  in  the  flame  of  the 
burner  till  the  magnesium  is  ignited.  Magnesium 
oxide  is  formed.  Write  the  reaction.  Prepare  a 
bottle  of  carbon  dioxide  and  thrust  into  it  a  piece  of 
burning  magnesium  ribbon.  Does  the  burning  con- 
tinue ?  Are  the  products  of  combustion  the  same  as 
when  magnesium  burns  in  the  air?  This  experiment 
shows  the  affinity  of  magnesium  for  oxygen. 

In  a  piece  of  charcoal  make  a  hole  large  enough 
to  hold  a  half  pea.  Fill  with  magnesium  oxide 
slightly  moistened  with  water.  Now  heat  strongly 
before  the  blowpipe,  cool,  moisten  with  one  drop  of 
cobaltous  nitrate,  and  heat  again.  Do  you  obtain  a 

91 


92  TEE  MORE  IMPORTANT  METALS. 

red-brown   color?      This  is  a  test    for    magnesium 
oxide. 

(b)  Zinc. 

Put  a  little  zinc  in  a  test-tube  and  treat  with  dilute 
hydrochloric  acid.  Repeat,  using  dilute  sulphuric 
acid.  Reactions  ?  Heat  a  little  zinc  on  charcoal  in 
the  oxidizing-flame  of  the  blowpipe.  Note  the  white 
coating  of  zinc  oxide  (ZnO)  on  the  charcoal.  Reac- 
tion ? 

Treat  a  little  zinc  oxide  just  as  you  did  magnesium 
oxide.  Note  the  color  when  hot,  when  cold,  after 
treatment  with  cobaltous  nitrate  and  heating  a  second 
time. 

How  is  zinc  obtained  from  its  ores  ? 

(c)  Cadmium. 

Procure  from  your  instructor  three  pieces  of  cad- 
mium. (The  entire  amount  need  not  exceed  £  grm.  in 
weight.)  Heat  one  piece  in  an  ignition-tube.  Does 
it  melt  at  a  comparatively  low  temperature  ?  Allow 
to  cool  and  then  put  on  charcoal  and  heat  in  the  oxi- 
dizing-flame. What  do  you  notice?  What  is  the 
color  of  cadmium  oxide  (CdO)  ? 

Test  a  piece  of  cadmium  with  dilute  hydrochloric 
acid.  Cadmium  chloride  (CdCla)  is  formed.  Reac- 
tion? 

Test  another  piece  with  dilute  sulphuric  acid.  Re- 
action? To  a  few  drops  of  a  solution  of  cadmium 
chloride  add  ammonium  sulphide.  What  is  the  color 
of  the  cadmium  sulphide  (CdS). 

(d)  Mercury. 

Give  the  physical  properties  of  mercury.  At  what 
temperature  does  it  melt?  Try  the  action  of  dilute 


MAGNESIUM,  ZINC,  CADMIUM,  AND  MERCURY.      93 

hydrochloric  acid  on  a  drop  of  mercury.  Does  the 
metal  dissolve  ? 

To  a  little  mercurous  nitrate  (HgNO,)  solution  add 
a  little  dilute  hydrochloric  acid :  mercurous  chloride 
(HgCl)  is  precipitated.  Write  the  reaction.  Re- 
peat the  same  experiment,  using  mercuric  nitrate 
(Hg(NO8)2)  solution.  Is  a  precipitate  formed? 
Which,  then,  is  soluble  in  water,  mercurous  chloride 
(calomel)  or  mercuric  chloride  (corrosive  sublimate)  ? 

Place  in  a  few  cc.  of  any  mercury  salt  solution  a 
piece  of  bright  copper ;  withdraw  after  a  few  minutes 
and  rub  with  a  cloth.  Explain  what  you  observe. 

Make  a  list  of  the  elements  studied  in  this  exercise 
in  the  order  of  their  atomic  weights.  Give  their 
atomic  weights.  Compare  the  metals  in  respect  to 
the  following  properties :  specific  gravity,  melting, 
point,  ease  with  which  they  are  attacked  by  acids. 

Show  in  what  relation  these  properties  stand  to 
the  atomic  weights. 

References :  Clk.,  pp.  223-231 ;  Cly.,  pp.  223,  224, 
236-237;  E.,  pp.  319-324,  330,  331;  S.,  pp.  316,  317, 
298,  300,  262,  263,  233,  237 ;  S.  and  L.,  pp.  325-337, 
347-350;  W.,  pp.  301-305,  339,  340,  356-358. 


EXERCISE  34. 

COPPEE,  SILVER,  AND  GOLD. 
(a)   Copper. 

To  a  solution  of  copper  sulphate  add  a  little  cold 
sodium  hydrate  solution.  Copper  hydrate  (Cu(OH)2) 
is  formed.  Write  the  reaction.  Add  to  a  solution  of 
copper  sulphate  a  drop  or  two  of  dilute  ammonia.  What 
do  you  notice  ?  Now  add  excess  of  ammonia.  What 
color  is  produced  ?  To  2  or  3  cc.  of  water  add  a  drop 
of  copper  sulphate  solution,  then  a  drop  of  potassium 
ferrocyanide  solution.  Note  the  color  of  the  copper 
ferrocyanide.  This  is  a  very  delicate  test  for  copper. 
To  a  few  drops  of  copper  sulphate  solution  add  1  cc. 
of  a  solution  of  tartaric  acid,  then  sodium  hydrate 
solution  till  the  solution  is  strongly  basic.  Now  add 
a  little  grape-sugar  and  boil.  Cuprous  oxide  (Cu20) 
is  precipitated.  Describe  it.  To  a  little  copper 
sulphate  solution  add  a  drop  of  dilute  hydrochloric 
acid,  then  a  piece  of  bright  iron  (wire  nail).  Examine 
after  a  few  minutes.  How  do  you  account  for  the 
appearance  of  the  nail  ? 

Heat  a  little  bright  copper  in  the  flame  of  the 
burner.  Does  it  oxidize?  Test  the  solubility  of 
copper  in  dilute  nitric  acid.  Write  the  reaction.  (See 
Exercise  17.) 

What  use  is  made  of  copper  in  the  arts?  What 
are  some  of  the  most  important  alloys  of  copper? 
How  is  copper  found  in  nature  ? 

94 


COPPER,  SILVER,  AND  GOLD.  95 

(5)  Silver. 

To  a  little  silver  nitrate  solution  add  an  equal 
volume  of  dilute  hydrochloric  acid.  Reaction  ?  Pour 
off  the  liquid  and  dissolve  the  precipitate  in  ammonia. 
Now  add  nitric  acid.  What  appears?  Collect  the 
precipitate  on  a  very  small  filter,  wash  with  distilled 
water  and  allow  to  drain  well.  Now  add  to  the  pre- 
cipitate its  own  volume  of  dry  sodium  carbonate,  and 
roll  the  filter  and  contents  into  a  ball  (size  of  a  pea). 
Heat  this  on  charcoal  before  the  blowpipe  till  the 
paper  is  consumed.  If  the  silver  appears  in  scattered 
deposits,  scrape  them  together  and  fuse  into  a  single 
bead.  Does  silver  oxidize  when  heated  in  the  air? 
Try  the  solubility  of  the  silver  bead  in  nitric  acid. 
Why  is  silver  classed  among  the  noble  metals  ?  What 
is  "  coin  silver  "  ?  "  sterling  silver  "  ? 

(c)  Gold. 

See  text-book  for  the  properties  of  gold. 

Does  gold  oxidize  when  heated  ?  Does  it  dissolve 
in  any  simple  acid?  Compare  it  with  silver  and 
with  copper  in  these  respects.  What  is  the  composi- 
tion of  the  alloy  of  which  gold  coins  are  made? 
What  is  meant  by  the  term  18-carat  gold  ? 

References:  Clk.,  pp.  275-279,  196-203,  280-281; 
Cly.,  pp.  233-236,  237-245 ;  E.,  pp.  325-329,  332-336, 
378-381 ;  S.,  pp.  258-261,  228-233,  266-267 ;  S.  and 
L.,  pp.  341-346,  350-356,  383-385;  W.,  pp,  340-343, 
349-356,  369-361. 


EXERCISE  35. 

ALUMINIUM  (OR  ALUMINUM). 

Procure  two  small  pieces  of  the  metal  from  your  in- 
structor. Test  the  solubility  (using  one  piece)  with 
dilute  hydrochloric  acid.  Aluminium  chloride  (A1C13) 
remains  in  solution.  Write  the  reaction.  Test  the 
solubility  of  aluminium  in  dilute  sodium  hydrate  solu- 
tion. Sodium  aluminate  (NaAlO2)  remains  in  solu- 
tion. Write  the  reaction.  Describe  the  physical 
properties  of  aluminium. 

To  a  solution  of  aluminium  sulphate  (Ala(S04),)  add 
ammonium  hydrate.  Aluminium  hydrate  (Al(OH)a) 
is  precipitated.  Write  the  reaction.  Filter  and 
heat  the  precipitate  on  charcoal  before  the  blow- 
pipe, moisten  with  a  little  cobaltous  nitrate  and  heat 
again.  Note  the  color.  This  is  a  test  for  aluminium. 

Alum  is  a  good  example  of  a  "double  salt." 

Dissolve  with  the  aid  of  heat  10  grms.  of  aluminium 
sulphate  in  as  little  water  as  will  effect  solution. 
Now  dissolve  2.6  grms.  of  potassium  sulphate  in  the 
same  manner  and  mix  the  hot  saturated  solutions  of 
the  two  salts.  Crystals  of  alum  (A1K(SO4)3.12H3O) 
will  form  on  cooling.  Filter  off  the  crystals  from  the 
mother-liquor  and  show  to  the  instructor.  How  can 
you  show  that  they  contain  aluminium  ?  (See  reac- 

96 


ALUMINIUM.  97 

tions  above.)  How  can  you  prove  that  they  contain 
potassium  ?  (See  flame-test,  Exercise  30.) 

How  is  aluminium  reduced  from  its  ores  ?  Give 
uses  of  the  metal ;  of  its  alloys. 

References:  Clk.,  pp.  232-236;  Cly.,  pp.  221-223 
E.,  pp.  339-348 ;  S.,  pp.  286-290;  S.  and  L.,  pp.  357- 
363 ;  W.,  pp.  313-317. 


EXERCISE  36. 
TIN  AND  LEAD. 

(a)  Tin. 

Give  the  physical  properties  of  the  metal.  Put 
about  |  grm.  of  granulated  tin  into  a  test-tube  and 
add  hydrochloric  acid.  The  tin  dissolves  in  the  acid, 
forming  a  solution  of  stannous.  chloride  (SnCl,).  Af- 
ter the  greater  part  of  the  tin  has  dissolved,  pour  off 
the  solution  from  the  undissolved  metal.  To  this 
solution  add  a  few  drops  of  mercuric  chloride  solu- 
tion. Now  heat.  The  precipitate  varies  from  white 
to  grayish  black,  depending  on  the  temperature  and 
the  proportion  of  each  reagent  added.  The  reactions 
may  be  expressed  as  follows : 

2HgCl2  +  SnCla  =  2HgCl  (white  ppt.)  +  SnCl4  (sol.). 
2HgCl  +  SnCl,  =  2Hg  (dark  gray)  +  SnCl4  (solution). 
This  is  a  delicate  test  for  both  tin  and  mercury. 

To  a  little  tin  add  moderately  concentrated  ni- 
tric acid.  What  do  you  notice?  Metastannic  acid 
(HjSnOj)*  is  formed.  Is  it  soluble  in  water  ?  Filter, 
wash  and  drain  well.  Now  heat  a  little  in  a  porcelain 
crucible  to  a  high  temperature.  Stafinic  oxide  is 
formed.  Write  the  reaction. 

What  use  is  made  of  tin  in  the  arts?  What  is 
bronze  ? 

(b)  Lead. 

Dissolve  \  grm.  of  lead  in  nitric  acid  in  the  follow- 
ing manmer :  Place  the  lead  in  an  evaporating-dish 


TIN  AND  LEAD.  99 

containing  a  few  cc.  of  water.  Heat  to  boiling  and 
add  concentrated  nitric  acid  till  vigorous  action  takes 
place.  Now  set  under  the  hood  and  allow  to  stand  till 
action  nearly  ceases.  If  undissolved  lead  is  present, 
add  a  little  more  acid  and  warm.  If  this  does  not 
cause  action  to  begin  again,  add  a  little  more  water. 
In  order  to  dissolve  lead  readily  there  must  be  acid 
enough  to  unite  with  the  lead,  and  water  enough  to 
hold  in  solution  the  lead  nitrate  formed.  When  solu- 
tion is  effected,  evaporate  nearly  to  dryness  and  dis- 
solve the  residue  in  500  cc.  of  water.  Suspend  in  this 
solution  a  strip  of  zinc  and  allow  it  to  remain  for  an 
hour.  What  do  you  notice  ?  Complete  the  reaction : 

Zn  +  Pb(NO3)a  =  Pb  +  . . . 

To  a  solution  of  lead  nitrate  (Pb(NO8)a  add  dilute 
sulphuric  acid.  Write  the  reaction.  To  another  por- 
tion of  the  nitrate  solution  add  a  solution  of  potassium 
chromate  (K2CrO4).  Lead  chromate  is  formed.  Write 
the  reaction. 

Warm  a  little  red  lead  (Pb,O4)  with  dilute  nitric  acid 
in  excess.  Brown  lead  peroxide  (PbO2)  is  left  undis- 
solved. 

How  is  lead  reduced  from  its  ores?  What  use 
is  made  of  lead  in  the  arts  ?  What  are  some  of  the 
more  important  alloys  of  lead  ? 

References:  Clk.,  pp.  239-245;  Cly.,  pp.  230,  232, 
233;  E.,  pp.  349-357;  8,  pp.  251-254,  224-228;  S. 
and  L.,  pp.  381-383,  337-341 ;  W.,  pp.  331-335,  334- 
349. 


EXERCISE  37. 

CHROMIUM. 

(a)    Chromates. 

In  these  compounds  chromium  has  an  acid  character.  Chromic 
acid  (hydrogen  chromate  (H2CrO4))  is  known  only  in  solution.  The 
salts  of  this  acid  are  similar  in  structure  and  crystalline  form  to  the 
salts  of  sulphuric  acid. 

Dissolve  a  few  crystals  of  potassium  chromate  in 
water,  and  to  separate  portions  add  in  solution : 
silver  nitrate,  barium  chloride,  lead  nitrate.  Reaction 
for  silver  nitrate  : 

K2CrO4  +  2AgN03  =  2KNO9  +  Ag9CrO4. 

Now  write  the  other  two  reactions,  remembering  that 
one  atom  of  lead  or  barium  can  replace  two  atoms  of 
potassium. 

To  about  1  cc.  of  potassium  chromate  solution  add 
a  few  drops  of  any  dilute  acid  on  your  desk.  Note 
change  of  color.  Potassium  bichromate  is  formed. 
Complete  the  following  : 

2KaCrO4  +  2HC1  =  K,Cr,O7  +  .  .  . 

To  this  solution  add  a  solution  of  potassium  hydrate 
till  the  color  just  changes  to  yellow.  Potassium 
chromate  (K2CrO4)  is  again  formed.  Write  the 
reaction. 

(b)   Chromic  Compounds. 

When  chrornates  are  reduced,  i.e.  lose  oxygen,  the  acid  character 
of  chromium  disappears.  Chromium  in  chromic  compounds  has  a 
basic  character. 

100 


CHROMIUM.       i~  5  - 

To  about  1  cc.  of  a  solution  of  potassium  bichromate 
add  a  little  concentrated  hydrochloric  acid  and  a  few 
drops  of  alcohol.  Warm  and  note  change  of  color. 
Eepeat,  using  a  little  oxalic  acid  instead  of  alcohol. 

To  a  solution  of  chrome  alum  add  ammonia.  The 
reaction  is  as  follows  : 

CrK(S04)9  +  3NH4OH 

-  KNH4S04  +  (NHg),S04  +  Cr(OH), 

Mix  a  little  (£  grm.)  dry  sodium  carbonate  with  an 
equal  quantity  of  potassium  nitrate  and  half  as  much 
chrome  alum.  Heat  strongly  in  a  porcelain  crucible 
for  some  time,  cool  and  dissolve  in  water.  If  the 
oxidation  is  complete  the  solution  will  appear  yellow. 
To  the  solution  add  dilute  nitric  acid  till  it  just  begins 
to  turn  orange-red.  Add  now  a  few  drops  of  silver 
nitrate  solution ;  a  red-brown  precipitate  shows  the 
presence  of  a  chromate. 

Fuse  a  piece  of  platinum  wire  into  a  piece  of  glass 
tube  ;  the  shape  is  shown  in  Fig.  22. 


FIG.  22. 

Heat  the  wire  loop  in  the  flame,  and  bring  it  into 
contact  with  a  small  crystal  of  borax.  Fuse  this  to  a 
globule,  continuing  the  process  till  you  have  a  clear 
bead  of  borax  glass  just  large  enough  to  be  held  in  the 
loop. 

Fuse  into  this  bead  a  minute  quantity  of  chrome 
alum,  just  enough  to  give  a  decided  color,  not  enough 
to  make  it  opaque.  "What  do  you  notice  ?  This  is  a 
delicate  test  for  chromium. 

References  :  Clk.,  pp.  252-256 ;  E.,  pp.  372-375  ;  S., 
pp.  282-285 ;  S.  and  L.,  pp.  378,  379  ;  W.,  pp.  317-320. 


EXERCISE  38. 

MANGANESE. 

(a)  Oxidizing  Action  of  Permanganates. 

Dissolve  a  crystal  of  potassium  permanganate 
(KMnO4)  in  10  cc.  of  water.  Place  in  a  beaker  and 
heat  nearly  to  boiling.  To  the  hot  solution  add, 
a  drop  at  a  time,  a  solution  of  oxalic  acid  containing 
a  little  sulphuric  acid.  Is  the  color  discharged? 
Repeat,  using  a  solution  of  ferrous  sulphate  containing 
sulphuric  acid  in  place  of  the  oxalic  acid  solution. 

To  a  few  crystals  of  potassium  permanganate  in  an 
evaporating-dish  add  a  few  drops  of  concentrated  sul- 
phuric acid.  Put  1  cc.  of  strong  alcohol  in  a  dry 
beaker  and  pour  it  upon  the  mixture  just  made. 
What  do  you  notice  ? 

To  a  few  crystals  of  potassium  permanganate  in  a 
test-tube  add  concentrated  hydrochloric  acid.  Is  the 
acid  oxidized  ?  If  so,  what  gas  is  liberated  ?  How  do 
you  recognize  it? 

(&)  Manganous  Compounds, 

To  a  solution  of  manganous  sulphate  add  sodium 
hydrate.  Manganous  hydrate  is  formed.  Complete 
the  reaction  :  MnSO4  +  2NaOH  =  .  .  . 

Allow  the  precipitate  to  stand  exposed  to  the  air  till 
it  changes  in  color.  Manganic  hydrate  (Mn(OH)8)  is 

formed. 

102 


MANGANESE.  103 

To  a  solution  of  manganous  sulphate  add  a  solution 
of  ammonium  sulphide.  Manganous  sulphide  (MnS) 
is  precipitated.  Describe  precipitate  and  write  re- 
action. 

Test  any  manganese  compound  in  the  borax  bead. 
(See  Exercise  37.)  What  color  is  imparted  to  the 
borax  glass  ? 

What  are  some  of  the  uses  of  manganese  com- 
pounds ? 

References:  Clk.,  pp.  262-264;  K.,  pp.  369-371 ;  S., 
pp.  295-298 ;  S.  and  L.,  pp.  363-365 ;  W.,  pp.  298-301. 


EXERCISE  39. 

IKON,  COBALT,  NICKEL,  AND  PLATINUM. 

(a)  Iron  in  Ferrous  Compounds. 

Put  about  3  grms.  of  iron  turnings  into  a  test-tube 
and  add,  a  little  at  a  time,  about  10  cc.  dilute  hydro- 
chloric acid.  Ferrous  chloride  (FeCl2)  is  formed. 
Reaction.  Allow  to  stand  till  action  nearly  ceases, 
then  pour  off  the  solution,  about  1  cc.  at  a  time,  and 
test  its  action  with  solutions  of  the  following  reagents  : 
(1)  sodium  hydrate ;  (2)  potassium  ferrocyanide  ;  (3) 
potassium  ferricyanide.  Describe  results.  Write  re- 
action for  (1).  Allow  this  precipitate  to  stand  exposed 
to  the  air.  Ferric  hydrate  (Fe(OH)3)  is  formed. 

(b)  Iron  in  Ferric  Compounds. 

Try  the  action  of  ferric  chloride  (FeCl,)  solution  on 
reagents  (1),  (2),  and  (3).  Describe  results  and  write 
reaction  for  (1).  To  about  1  cc.  of  a  solution  of  fer- 
rous chloride  add  a  few  drops  of  concentrated  nitric 
acid  and  boil.  The  solution  should  now  be  light 
yellow  in  color.  If  it  is  green  or  dark,  repeat  the 
process.  Avoid  an  excess  of  acid.  Now  prove  by  the 
action  of  reagents  (1),  (2),  and  (3)  that  ferrous  iron  has 
been  oxidized  to  ferric  iron. 

What  are  the  most  important  ores  of  iron  ?  What  is 
cast  iron  ?  wrought  iron  ?  steel  ? 

104 


IRON,  COBALT,  NICKEL,  AND  PLATINUM.       105 

(c)  Cobalt 

To  1  cc.  of  a  solution  of  cobaltous  chloride  add 
sodium  hydrate  solution  and  boil.  Cobaltous  hydrate 
is  precipitated.  Write  the  reaction.  (See  analogous 
reation  of  FeCla  -f  2NaOH.)  What  color  is  imparted 
to  the  borax  bead  by  cobalt  compounds? 

(d)  Nickel 

Treat  a  solution  of  nickel  sulphate  (NiSO4)  with 
sodium  hydrate  solution.  What  is  formed  ?  Keaction. 
What  color  is  imparted  to  the  borax  bead  by  nickel 
compounds  ? 

What  use  is  made  of  nickel  in  the  arts  ?  What  are 
some  of  the  most  important  alloys  of  nickel?  Of 
what  does  "nickel"  used  for  coinage  consist? 

(e)  Platinum. 

What  properties  of  platinum  have  you  observed? 
Why  is  it  valuable  for  use  in  the  laboratory  ?  How 
is  it  found  in  nature  ? 

JReferences:  Clk.,  pp.  264-271,  273,  274,  282-284; 
Cly.,  pp.  224-230,  244;  E.,  pp.,  358-368,  376-378;  S., 
pp.  275-282,  290-295,  268,  269 ;  S.  and  L.,  pp.  366, 
378,  385-388 ;  W.,  pp.  306-313,  294-298,  361. 


SOME  FAMILIAR  HYDROCARBONS 
AND  THEIR  DERIVATIVES. 

SO-CALLED  ORGANIC  COMPOUNDS. 


EXERCISE  40. 

SOME  HYDROCARBONS. 

(a)   The  Methane  Series. 

This  series  has  the  general  formula  CnH2n  +  2.  It  is 
rather  difficult  to  prepare  the  lower  members.  Con- 
sult text  and  reference-books  for  the  preparation  and 
properties  'of  the  first  member,  methane  (CH4).  Ex- 
amples of  the  higher  members  are  benzine,  gasoline, 
kerosene,  and  paraffine. 

The  greater  part  of  gasoline  consists  of  heptane 
(C7H16)  and  octane  (C6H]8).  Place  four  drops  of  gaso- 
line in  an  evaporating-dish.  (Keep  bottle  of  gasoline 
away  from  flames.)  Place  the  dish  under  the  hood 
and  apply  a  lighted  splinter.  Note  the  character 
of  the  flame. 

Now  repeat  the  same  experiment,  using  kerosene 
instead  of  gasoline.  (Kerosene  consists  principally  of 
hydrocarbons,  CiaHa8  to  C]6H34  inclusive.)  Which 
can  you  light  the  most  readily,  gasoline  or  kerosene  ? 
Which  burns  with  the  higher  flame?  Which  flame  is 
the  more  sooty  ?  What  relation  does  the  number  of 
carbon  atoms  bear  to  the  volatility  of  the  hydrocarbon? 

When  any  hydrocarbon  is  completely  burned,  water 
and  carbon  dioxide  are  the  only,  products  formed. 
Write  the  reaction  representing  the  combustion  of 
hexane  (CeH14).  What  is  the  composition  of  American 
petroleum?  (See  reference-books  or  cyclopedia.) 

109 


110  SOME  FAMILIAR  HYDROCARBONS. 

(b)  Acetylene  (CtHt). 

This  hydrocarbon  belongs  to  the  series  CnH2n_2. 

Fill  a  test-tube  one  fourth  full  of  water  and  drop 
into  it  two  or  three  pieces  of  calcium  carbide  (CaCa)  as 
large  as  peas.  Light  the  escaping  gas.  Note  the  ap- 
pearance of  the  flame.  "Write  the  reaction  repre- 
senting the  combustion  of  acetylene. 

After  action  in  the  tube  has  ceased  test  the  con- 
tents of  the  tube  with  red  litmus  paper.  Have  you 
reason  to  think  that  calcium  hydrate  (Ca(OH)3)  is 
present?  If  so,  write  the  reaction  representing  the 
action  of  water  on  calcium  carbide  resulting  in  the 
liberation  of  acetylene. 

References:  Oik.,  pp.  79-83,  296,  297  ;  Cly.,  pp.  183- 
186;  E.,  pp.  384-389;  S.,  pp.  132-135;  S.  and  L., 
pp.  196-206,  238,  239 ;  W.,  pp.  363-370. 


EXERCISE  41. 

SOME  HALOGEN  DERIVATIVES  OF  THE  HYDROCARBONS. 

(a)  Chloroform  (CHCl,). 

Chloroform  may  be  made  by  treating  methane  with 
chlorine.  It  is  regarded  as  methane  in  which  three 
chlorine  atoms  have  been  substituted  for  three  hydro- 
gen atoms. 

Pour  about  3  cc.  of  chloroform  into  a  test-tube 
provided  with  a  cork  stopper,  and  use  for  the  follow- 
ing tests :  Put  a  few  drops  into  a  dry  test-tube  and 
warm.  Note  the  odor.  Will  the  vapor  burn  ?  To  a 
few  cc.  of  water  in  a  test-tube  add  a  few  drops  of 
potassium  iodide  solution  and  a  minute  crystal  of 
iodine.  When  solution  is  effected  add  a  few  drops 
of  chloroform  to  the  colored  solution,  shake  vigor- 
ously, and  allow  to  settle.  What  do  you  notice  ?  Is 
chloroform  a  good  solvent  for  iodine  ?  for  gums  and 
oils?  Try  its  action  on  a  little  paraffine.  What  is 
the  principal  use  of  chloroform  ? 

(b)  lodoform  (CHI3). 

Place  in  a  test-tube  1  cc.  of  ordinary  (ethyl)  alcohol 
and  add  2  grms.  of  iodine.  Now  dissolve  in  a  small 
beaker  or  test-tube  about  3  grms.  of  potassium  car- 
bonate (or  sodium  carbonate)  in  a  small  quantity  of 
hot  water.  Add  this  to  the  iodine  in  the  alcohol, 
drop  by  drop,  till  the  brown  color  disappears.  Boil 
the  mixture  till  any  pieces  of  iodine  that  may  be  in 

111 


112  SOME  FAMILIAR  HYDROCARBONS. 

the  bottom  of  the  tube  are  dissolved.  If  the  solution 
becomes  brown,  add  a  drop  or  two  more  of  the  carbon- 
ate solution.  Now  heat  to  boiling,  set  aside,  and 
allow  to  cool.  Yellow  crystals  of  iodoform  should 
separate  out.  For  what  is  iodoform  used  ? 

References :  Clk.,  pp.  302  ;  R.,  pp.  387,  388 ;  S.  and  L., 
pp.  197,  198 ;  W.,  pp.  366. 


EXERCISE  42. 

ALCOHOL. 

An  alcohol  may  be  defined  as  a  hydrocarbon  in  which  hydrogen 
(H)  has  been  replaced  by  hydroxyl  (OH). 

(a)  Methyl  Alcohol  (CH3OH). 

Procure  1  cc.  of  methyl  alcohol  (or  wood  spirit) 
and  note  odor.  Draw  some  of  the  vapor  (not  the 
liquid)  into  the  mouth  and  note  the  taste.  Do  you 
think  that  this  alcohol  would  admit  of  use  in  bever- 
ages ?  What  is  "  methylated  spirit "  ?  Will  methyl 
alcohol  burn  ?  If  so,  write  the  reaction. 

(b)  Ethyl  Alcohol  (C\H6OH). 

Put  20  grms.  of  commercial  glucose  or  30  grms.  of 
"  corn-syrup  "  into  a  250-cc.  flask,  add  about  150  cc. 
of  water  and  one  fourth  of  a  cake  of  "  compressed  " 
yeast.  Fermentation  should  begin  promptly,  accord- 
ing to  the  reaction : 

C6H1206     =     2C,H6OH    +    2C02. 

Grape-sugar  Alcohol  Carbon  dioxide 

To  prove  that  carbon  dioxide  is  given  off  conduct 
the  escaping  gas  into  lime-water  as  shown  in  Fig.  23. 
Cover  the  lime-water  with  a  thin  layer  of  kerosene  to 
protect  it  from  the  action  of  carbon  dioxide  in  the 
air.  Be  sure  that  the  cork  in  the  flask  is  perfectly 
tight,  otherwise  the  gas  will  gradually  diffuse  into  the 

113 


114 


SOME  FAMILIAR  HYDROCARBONS. 


FIG.  23. 


air  instead  of  passing  into  the  lime-water.  Set  aside 
for  several  days.  Does  the  lime-water  become  cloudy  ? 
If  so,  give  the  reaction.  Now  filter  the  contents  of  the 
flask.  The  filtrate  consists  of  some  un- 
changed glucose,  alcohol,  and  traces  of 
other  products  dissolved  in  a  large  ex- 
cess of  water.  The  alcohol  may  be  ob- 
tained in  purer  condition  and  more 
concentrated  form  by  distilling. 

Set  up  apparatus  as  shown  in  Fig.  18. 
Pour  into  the  retort  about  one  half  as 
much  of  the  filtrate  as  it  will  hold  and 
then  drop  in  a  few  pieces  of  granulated  zinc  to 
prevent  "  bumping." 

Distil  over,  very  cautiously,  about  one  fourth  of 
the  liquid  in  the  retort,  keeping  the  test-tube  used  as 
a  receiver  well  cooled.  This  distillate  contains  nearly 
all  the  alcohol  of  the  liquid  placed  in  the  retort  along 
with  considerable  water.  Save  the  distillate ;  throw 
away  the  liquid  remaining  in  the  retort.  Repeat  the 
process  till  all  the  alcohol  in  the  filtrate  has  been  dis- 
tilled off.  If  directions  have  been  followed,  you  have 
now  distilled  off  40  to  50  cc.  of  dilute  alcohol.  Now 
wash  the  retort,  and  in  it  place  this  dilute  alcohol. 
Distil  off  about  10  cc.  You  should  now  have  the  al- 
cohol in  a  fairly  concentrated  form.  Put  1  cc.  of  this 
alcohol  into  a  test-tube,  add  a  few  crystals  of  iodine, 
and  then  potassium  carbonate  solution.  See  method 
of  making  iodoform  in  Exercise  40,  The  formation 
of  iodoform  shows  the  presence  of  alcohol. 

Put  the  rest  of  the  alcohol  in  a  beaker  and  gradually 
heat  to  boiling.  Apply  a  light  to  the  vapor.  If  the 
alcohol  does  not  contain  too  much  water  its  vapor  will 
burn.  Write  the  reaction. 


ALCOHOL.  115 

Note. — Conditions  affecting  Fermentation.  The  yeast  must  be  fresh. 
"  Compressed  "  yeast  gives  better  results  than  dry  yeast.  Fermen- 
tation requires  air  at  the  start,  hence  do  not  make  the  test  for  carbon 
dioxide  till  the  gas  begins  to  come  off  freely.  The  proper  tempera- 
ture is  20°-30°  C.  (68°-86°  F.).  Sunlight  is  unfavorable.  Disin- 
fectants, as  certain  salts,  carbolic  acid,  etc.,  kill  the  yeast-cells. 
Impure  sugars  or  syrups  contain  albuminoids  and  phosphates,  hence 
they  ferment  more  readily  than  pure  sugars. 

References:  Clk.,  pp.  298-300;  Cly.,  pp.  186-189; 
K,  pp.  389-391,  400,  401;  S.  and  L.,  pp.  210-214; 
W.,  pp.  865,  366,  370,  371. 


EXERCISE  43. 
SOME  FATTY  ACIDS. 

These  acids  are  called  "fatty  acids"  because  some  of  the  higher 
members,  combined  with  glycerin,  constitute  a  considerable  portion 
of  animal  and  vegetable  oils.  Hence  the  hydrocarbons  from  which 
they  are  derived  are  called  "  fatty  "  hydrocarbons. 

(a)  Acetic  Add  (H(C9H,Ot)). 

Set  up  apparatus  as  in  Fig.  18.  Place  a  few  pieces 
of  glass  in  the  retort  and  add  about  30  cc.  of  strong 
vinegar.  Distil  off  the  greater  part  of  the  liquid. 
Taste  the  distillate. 

Try  its  action  on  blue  litmus  paper ;  on  sodium 
carbonate  solution.  Complete  the  reaction  : 

Na,CO,  +  2H  (C.H.O.)  =  .  .  . 

To  a  little  of  the  distillate  add  a  few  drops  of  ferric 
chloride  solution.  Note  color  of  solution. 

(b)  Soap. 

Soap  consists  principally  of  the  sodium  (or  potassium)  salts  of  the 
higher  fatty  acids.  Thus  we  may  assume  that  a  pure  white  soap 
consists  of  sodium  palmitate  (Na  (C16H3i02)  )  and  sodium  stearate 
(Na(Ci8H3502)).  Since  this  latter  compound  predominates  we  will 
use  it  in  writing  all  reactions  in  this  section. 

Weigh  out  5  grms.  of  any  white  soap  ("  Ivory"  soap 
is  good),  and  cut  into  fine  shavings.  Dissolve  these  in 
100  cc.  of  distilled  water,  heating  if  necessary.  If  the 
solution  is  not  perfectly  clear,  filter. 

Make  a  saturated  solution  (5  cc.)  of  common  salt, 

116 


SOME  FATTY  ACIDS.  117 

and  to  this  solution  add  an  equal  volume  of  the  soap 
solution.  What  do  you  notice  ?  Soap  is  not  soluble, 
in  brine.  Explain  what  use  is  made  of  this  fact  in 
soap  manufacture. 

To  another  portion  of  the  soap  solution  add  a  few 
drops  of  magnesium  sulphate.  Eesult  ? 

Complete  the  reaction  MgSO4  +  2Na(C18H86Oa)  = 

Is  the  precipitate  soluble  in  water?  Explain  how 
magnesium  sulphate  makes  water  "  hard." 

Prepare  a  solution  of  acid  calcium  carbonate.  (See 
Exercise  32.)  Test  a  little  of  the  solution  with  the 
soap  solution.  Is  a  precipitate  formed  ? 

The  reaction  is : 

CaH,(CO,)J+2NaC18HaA=Ca(C1.H310,),+2NaHCO,. 

Now  boil  the  rest  of  the  acid  calcium  carbonate 
solution  for  several  minutes  and  filter.  Test  the  filtrate 
with  soap  solution.  Do  you  now  get  a  precipitate? 
Explain.  What  is  temporatory  hardness  in  water? 

To  the  rest  of  the  soap  solution  add  hydrochloric 
acid  to  decidedly  acid  reaction.  The  precipitate  con- 
sists of  stearic  acid  (with  other  acids).  Write  the  re- 
action. Is  this  acid  soluble  in  water? 

References:  Clk.,  pp.  303-306,  319-321;  Cly.,  p. 
206;  R,  pp.  393-396;  S.  and  L.,  pp.  215,  216,  224- 
227;  W.,  pp.  372,  373. 


EXERCISE  44. 
SOME  FAMILIAR  CARBOHYDRATES. 

(a)   Glucose  or  Grape-sugar  (C6H^O^). 

Prepare  Fehling's  test  for  glucose  as  follows :  Dis- 
solve about  1.8  grms.  of  crystallized  copper  sulphate  in 
25  cc.  of  water.  Label  this  solution  "I."  Dissolve  8 
grms.  of  Rochelle  salt  (sodium  potassium  tartrate)  in 
25  cc.  of  water.  To  this  solution  add  25  grms.  of  pure 
(solid)  sodium  hydrate  and  heat  gently  till  solution  is 
effected.  Label  this  solution  "II." 

To  5  cc.  of  solution  "  II "  add  an  equal  quantity  of 
solution  "I."  Place  in  a  small  beaker  and  heat  to 
boiling.  If  the  reagents  are  pure,  no  change  will  be 
noticed.  Now  add  a  little  glucose  and  heat  again. 
What  do  you  notice  ?  Cuprous  oxide,  containing  more 
or  less  water,  is  precipitated. 

(b)  Cane-sugar  (C^OJ. 

Warm  a  few  crystals  of  cane-sugar  with  a  drop  of 
concentrated  sulphuric  acid  and  note  result.  Test 
with  Fehling's  solution  as  in  (a),  using  cane-sugar  in- 
stead of  glucose.  If  no  precipitate  is  formed,  test 
with  a  few  drops  of  a  solution  of  cane-sugar  that  has 
been  boiled  with  a  drop  of  concentrated  hydrochloric 
acid.  Describe  results.  Explanation  :  Under  the  in- 
fluence of  the  acid  we  have 

C..H..O,,  +  H.O  =  C6H,  A  +  C.H..O.. 

Cane-sugar     +  Water   =  Grape-sugar  +  Fruit-sugar. 

118 


SOME  FAMILIAR  CARBOHYDRATES.  119 

(c)  Starch  (CtN1006)x. 

How  can  you  detect  starch  by  means  of  iodine? 
(See  Exercise  22.)  Prove  that  a  sample  labelled 
"  starch  "  really  contains  starch.  Work  out  the  details 
of  the  test  for  yourself.  Describe  results  fully. 

Does  starch  give  a  precipitate  with  Fehling's  solu- 
tion ?  Can  you  obtain  a  precipitate  by  first  converting 
starch  into  glucose  ?  Proceed  as  follows :  Put  a  little 
starch  into  a  test-tube  and  add  a  few  drops  of  con- 
centrated sulphuric  acid.  Allow  to  stand  for  a  few 
minutes,  then  add  a  little  water  and  boil. 

Does  a  little  of  this  reduce  Fehling's  solution  ? 

(d)  Cellulose  (C6H1006)V. 

Filter-paper  and  absorbent  cotton  are  examples  of 
nearly  pure  cellulose.  Is  cellulose  soluble  in  water 
or  dilute  acids  ?  Can  it  be  converted  into  glucose  ? 
Try  as  follows  :  Put  a  little  filter-paper  (a  round  filter 
7  cm.  in  diam.)  into  a  perfectly  dry  beaker  and  add  1 
cc.  of  concentrated  sulphuric  acid.  Using  a  glass  rod, 
thoroughly  stir  the  paper  into  at  hick  paste.  Allow  to 
stand  for  a  few  minutes,  then  add  2  cc.  of  water  and 
boil.  Nearly  neutralize  with  solid  sodium  carbonate, 
adding  a  little  water  from  time  to  time  in  quantity  suf- 
ficient to  dissolve  the  greater  part  of  the  sodium  sul- 
phate that  is  formed.  Test  this  solution  with  Fehling's 
solution. 

The  following  experiment  is  to  be  performed  if  ice 
or  snow  is  procurable.  Set  a  small  beaker  in  a  dish 
containing  pieces  of  ice  or  snow.  A/M  10  cc.  concen- 
trated nitric  acid  and  allow  to  cool.  Now  pour  in  20  cc. 
concentrated  sulphuric  acid  and  stir  with  a  glass  rod. 
Allow  the  mixed  acids  to  cool  and  then  introduce  a 


120*  SOME  FAMILIAR  HYDROCARBONS. 

tuft  of  absorbent  cotton  equal  in  volume  to  that  of  the 
mixed  acids.  Allow  to  stand  for  15  minutes,  remove 
with  a  glass  rod  and  wash  thoroughly.  Set  aside  and 
allow  to  dry.  Compare  it  with  absorbent  cotton. 
Place  an  equal  amount  of  absorbent  cotton  near  it  and 
apply  a  lighted  splinter  to  each.  What  do  you.  notice? 
For  what  is  nitrocellulose  used  ?  What  is  gun-cotton  ? 

Why  are  the  compounds  in  this  exercise  called 
carbohydrates  ? 

References:  Clk.,  pp.  322-328;  Cly.,  pp.  203,204; 
K.,  pp.  402-408 ;  S.  and  L.,  pp.  253-269. 


EXERCISE  45. 

A  FEW  AROMATIC  OR  BENZENE  DERIVATIVES. 

(a)  Benzene  or  Benzol  (O6H6). 

This  compound  is  not  to  be  confused  with  commercial  "  benzine." 

Note  the  odor  of  benzene.  Procure  a  few  drops  in 
an  evaporating-dish  and  apply  a  lighted  splinter. 
Note  the  appearance  of  the  benzene  flame. 

(b)  Nitrobenzene  (C6H,NO,). 

Perform  this  experiment  under  the  hood.  See  that  no  lighted 
burners  are  near.  Avoid  inhaling  the  fumes. 

Put  5  cc.  concentrated  nitric  acid  into  a  small  flask 
and  add  an  equal  volume  of  benzene.  Now  add,  a  drop 
at  a  time,  2  cc.  concentrated  sulphuric  acid,  stirring 
constantly.  In  case  the  mixture  becomes  hot  so  as  to 
seem  to  boil,  place  the  flask  in  cold  water.  When  all 
the  sulphuric  acid  has  been  added,  place  the  flask  in  a 
dish  containing  water  that  has  been  heated  to  boiling. 
Allow  to  stand  for  five  minutes,  and  then  pour  the 
contents  of  the  flask  into  cold  water.  Nitrobenzene 
sinks  to  the  bottom.  Pour  off  the  acid  solution  above 
it  and  add  more  water.  Stir  well,  allow  to  settle,  and 
pour  off  the  water.  Note  the  color  and  odor  of  nitro- 
benzene. Keaction :  C6H6  +  HNO3  ^  C6HBNO2  +  H,O. 
The  sulphuric  acid  helps  to  remove  the  water. 

121 


122  SOME  FAMILIAR  HYDROCARBONS. 

(c)  Aniline  (C&NHJ. 

Aniline  is  prepared  by  reducing  nitrobenzene  with 
iron  and  hydrochloric  acid.  Hydrogen  is  generated, 
which  reacts  as  follows : 

C6HBNO,  +  6H  =  C6HBNH,  +  2H3O. 

As  it  is  troublesome  to  separate  aniline  from  the 
products  formed,  it  is  better  to  use  prepared  aniline 
for  the  following  experiments :  Place  a  few  drops 
of  water  in  a  test-tube  and  add  an  equal  volume  of 
cone,  sulphuric  acid.  To  this  acid  solution  add  a  few 
drops  of  aniline,  mix,  and  cool.  Aniline  sulphate  is 
formed.  Describe  it. 

Put  2  grms.  of  fresh  bleaching-powder  in  10  cc.  of 
water.  Stir  well,  allow  to  stand  for  five  minutes,  and 
filter.  Dissolve  a  drop  or  two  of  aniline  in  10  cc.  of 
water  and  add  this  to  the  bleaching-powder  solution. 
Note  color.  This  is  a  test  for  aniline. 

(d)  JKosaniline. 

Put  a  few  drops  of  aniline  with  a  few  crystals  of 
fcoluidine  in  a  test-tube.  Add  a  few  crystals  of  mer- 
curic chloride  (corrosive  sublimate)  and  heat  for  a 
moment  over  the  open  flame.  Cool,  add  a  drop  of 
cone,  hydrochloric  acid,  then  1  cc.  of  alcohol.  Now 
dilute  with  water,  and  note  the  .color  imparted  to  the 
water. 

References  :  Clk.,  pp.  329-337  ;  E.,  pp.  408-411 ;  S. 
and  L.,  pp.  240-242. 


APPENDIX. 

INFORMATION  FOR  SCHOOLS  NEEDING  EQUIPMENT  FOR 
TEACHING  CHEMISTRY. 


APPENDIX. 

THE  following  is  a  list  of  the  apparatus  called  for  by 
the  manual.  As  it  stands  the  list  is  complete  for  one 
student.  It  is  desirable  that  all  items  marked  * 
should  be  multiplied  by  the  number  of  students  who 
are  expected  to  work  at  the  same  time. 

The  Denver  Fire-clay  Company,  3101-3141  Champa 
Street,  Denver,  Colo.,  will  supply  apparatus  and  chemi- 
cals at  the  prices  given. 

*  Asbestos  plate,  ¥  X  4" $0.05 

Balloon,  toy , * 05 

*  Beakers,  lipped,  Nos.  0,  2,  and  4 31 

*  Blowpipe,  plain,  brass,  10" 06 

*  Bottles,  8  and  4  oz.,  wide  mouth,  2  each 15 

*  Burner,  Bunsen,  w.  2  feet  hose 32 

*  Burner,  fishtail  only .10 

*  Burette  clamp 10 

Corks,  asst'd,  2  doz 10 

*  Cork-borers,  set  of  3 42 

*  Copper  wire,  10  gauge,  3  feet 05 

*  Crucible,  pore.,  w.  cover,  1J",  E.  M.,  No.  8 09 

*  Evaporating-dish,  pore.,  3" 09 

Files,  round  and  three-cornered 13 

*  Flasks,  flat  bottom,  250  and  500  cc 18 

*  Funnel,  3" 07 

*  Gauze,  wire,  4"  X  4" 05 

*  Glass  rod,  •&  diam.,  9*  long .05 

125 


126  APPENDIX. 

*  Glass  plate,  window-glass,  3"  X  3* $0.05 

Graduate,   50  cc.   cylinder 23 

*  Leaden  dish,  2"  diam 08 

Magnet,  horseshoe,  2" 05 

Magnifying-glass,  1  glass,  rubber  case 37 

Mortar  and  pestle,  W.  W.,  4  oz 19 

*  Pincers,  4" 05 

*  Picture-wire,  6" No  charge. 

Platinum  wire,  24  gauge,  3" , , . , ,      .24 

Platinum-foil,   med.,  Y  X  I" 60 

*  Pneumatic  trough,  5"  X  1"  X  10" 84 

Reagent  bottles,  set  of  eight,  4  oz. : 

Hydrochloric  acid  cone. 
Hydrochloric  acid  dil. 
Sulphuric  acid  cone. 


r 


.88 


Sulphuric  acid  dil. 
Nitric  acid  cone. 
Nitric  acid  dil. 
Sodium  hydrate. 
Ammonia. 

*  Retort,  50  cc.  with  glass  stopper 20 

*  Ring-stand,  w.  2  rings 34 

*  Test-tube  rack  for  6  tubes,  w.  pins 25 

*  Test-tubes,  16  X  160  mm.,  1  doz 16 

*  Test-tube,  one,  25  X  200mm  . .  „ 03 

*  Thistle-tube,  14" 06 

*  Tube,  rubber,  J",  6  inches 05 

*  Tubes,  soft  glass,  V  i.  d.,  5  tubes 10 

*  Tube,  hard  glass,  ±"  o.  d 05 

*  Triangle  for  1 J"  crucible,  pipe-stem 04 

*  Watch-glasses,  iy 05 

Alcohol-lamp,    2  oz 12 


APPENDIX.  127 

In  addition  to  the  apparatus  just  listed  a  number  of 
bottles  of  various  sizes,  and  a  few  large  beakers  and 
evaporating-disbes,  should  be  included  in  the  order. 
These  articles  will  be  needed  in  making  solutions 
of  reagents. 

The  laboratory  should  also  be  provided  with  a 
balance  accurate  to  .05  grm.,  a  set  of  weights,  an 
apparatus  for  distilling  water,  and  a  water-bath. 


O 


FIG.  24. 

In  case  the  building  is  heated  by  steam,  water  con- 
densed in  the  steam-pipes  may  usually  be  obtained 
from  the  engineer.  For  laboratories  not  supplied 
with  steam  or  with  running  water,  a  "  sanitary  "  still 
is  to  be  recommended.  Information  may  be  obtained 
from  A.  R.  Bailey  Mfg.  Co.,  54  Maiden  Lane,  N.  Y. 

A  water-bath  may  be  constructed  out  of  a  pan 
covered  with  a  sheet-iron  plate  as  shown  in  Fig.  24. 
The  small  circles  represent  holes  about  two  inches  in 
diameter  for  three-inch  evaporators.  The  circle  to 
the  right  represents  a  disk  about  three  inches  in 
diameter.  Five  of  these  should  be  provided  for 
covers. 

The  following  list  of  chemicals  is  estimated  on  the 
basis  of  ten  students.  As,  however,  it  is  not  profitable 


126  APPENDIX. 

*  Glass  plate,  window-glass,  3"  X  3* $0.05 

Graduate,   50  cc.   cylinder 23 

*  Leaden  dish,  2"  diam 08 

Magnet,  horseshoe,  2" 05 

Magnif ying-glass,  1  glass,  rubber  case 37 

Mortar  and  pestle,  W.  W.,  4  oz 19 

*  Pincers,  4" 05 

*  Picture-wire,  6" No  charge. 

Platinum  wire,  24  gauge,  3" > 24 

Platinum-foil,   med.,  Y  X  1" 60 

*  Pneumatic  trough,  5"  X  1"  X  10* 84 

Reagent  bottles,  set  of  eight,  4  oz. : 

Hydrochloric  acid  cone. 

Hydrochloric  acid  dil. 

Sulphuric  acid  cone. 

Sulphuric  acid  dil.  gg 

Nitric  acid  cone. 

Nitric  acid  dil. 

Sodium  hydrate. 

Ammonia. 

*  Retort,  50  cc.  with  glass  stopper , 20 

*  Eing-stand,  w.  2  rings 34 

*  Test-tube  rack  for  6  tubes,  w.  pins 25 

*  Test-tubes,  16  X  160  mm.,  1  doz 16 

*  Test-tube,  one,  25  X  200  mm 03 

*  Thistle-tube,  14" 06 

*  Tube,  rubber,  J",  6  inches 05 

*  Tubes,  soft  glass,  y  i.  d.,  5  tubes 10 

*  Tube,  hard  glass,  \"  o.  d 05 

*  Triangle  for  1 J"  crucible,  pipe-stem 04 

*  Watch-glasses,  \\" 05 

Alcohol-lamp,    2  oz 12 


APPENDIX.  127 

In  addition  to  the  apparatus  just  listed  a  number  of 
bottles  of  various  sizes,  and  a  few  large  beakers  and 
evaporating-dishes,  should  be  included  in  the  order. 
These  articles  will  be  needed  in  making  solutions 
of  reagents. 

The  laboratory  should  also  be  provided  with  a. 
balance  accurate  to  .05  grm.,  a  set  of  weights,  an 
apparatus  for  distilling  water,  and  a  water-bath. 


O 


FIG.  24. 

In  case  the  building  is  heated  by  steam,  water  con- 
densed in  the  steam-pipes  may  usually  be  obtained 
from  the  engineer.  For  laboratories  not  supplied 
with  steam  or  with  running  water,  a  "  sanitary  "  still 
is  to  be  recommended.  Information  may  be  obtained 
from  A.  E.  Bailey  Mfg.  Co.,  54  Maiden  Lane,  N.  Y. 

A  water-bath  may  be  constructed  out  of  a  pan 
covered  with  a  sheet-iron  plate  as  shown  in  Fig.  24. 
The  small  circles  represent  holes  about  two  inches  in 
diameter  for  three-inch  evaporators.  The  circle  to 
the  right  represents  a  disk  about  three  inches  in 
diameter.  Five  of  these  should  be  provided  for 
covers. 

The  following  list  of  chemicals  is  estimated  on  the 
basis  of  ten  students.  As,  however,  it  is  not  profitable 


128  APPENDIX. 

to  purchase  in  too  small  quantities,  many  of  the  sub- 
stances are  listed  in  amounts  sufficient  for  several 
classes  of  this  number.  Items  marked  *  are  not  in- 
cluded in  the  estimate  furnished  by  the  supply  house. 

CHEMICALS. 

Acetic  Acid,  No.  8,  and  bot.,  J  Ib $0.07 

*  Alcohol.    Procure  revenue-free  if  used  in  quan- 

tity. 

Alum,  potassium,  J  Ib .      .12 

Aluminium,  foil,  No.  34,  1  oz 06 

Aluminium  Sulphate,  J  Ib , » 05 

Ammonia,  aqua,  and  bot.,  5  Ibs 75 

Ammonium  Carbonate  and  bot.,  J  Ib 11 

Ammonium  Chloride,  gran.,  2  Ibs 22 

Ammonium  Molybdate  and  bot.,  1  oz 20 

Ammonium  Nitrate,  ^  Ib 10 

*  Ammonium  Sulphide.     To  be  made  in  the  labo- 

ratory. 

Animal  Charcoal,  gran.,  ^  Ib 10 

Aniline  Oil  and  bot.,  1  oz 10 

Antimony,  powdered,  2  oz 05 

Arsenic,  metallic,  1  oz 05 

Arsenic  Trioxide,  com.,  and  bot.,  1  oz 05 

Barium  Hydrate  and  bot.,  2  oz  , 18 

Barium  Chloride,  in  cart.,  J  Ib 10 

Benzene,  C6H6 ,  J  Ib 15 

Bleaching-powder,  small  can 09 

Blue-print  Paper,  4  X  5,  25  sheets,  1  pkge 15 

Bone-ash,  J  Ib 05 

Borax,  1  Ib 10 

Bromine  and  2  bots.  and  2  cans,  2  oz 40 

Beeswax,  2  oz 06 

Cadmium,  sticks  and  bot.,  J  oz ,15 


APPENDIX.  129 

Cadmium  Chloride  and  bot.,  1  oz $0.30 

Calcium  Carbide,  1  Ib 28 

Calcium  Chloride,  gr.,  and  bot.,  1  Ib 26 

Calcium  Fluoride,  powdered,  1  Ib 05 

Calcium  Hypophosphite,  J  Ib.  in  bot 42 

*  Calico,  red. 

*  Candles. 

Carbon  Bisulphide  and  can,  1  Ib 19 

Chalk,  precipitated,  £  Ib 07 

Charcoal,  10  sticks 25 

Chloroform  and  bot.,  J  Ib .25 

Chrome  Alum,  J  Ib 05 

Chromic  Acid  and  bot.,  J  Ib , 19 

Cobaltous  Chloride  and  bot.,  1  oz 20 

Cobaltous  Nitrate  and  bot.,  1  oz 52 

Copper  turnings,  1  Ib 35 

Copper  Oxide,  powder,  J  Ib 25 

Copper  Sulphate,  £  Ib. , 05 

*  Cotton,  absorbent. 

Ferric  Chloride  and  bot.,  2  oz 09 

Ferrous  Sulphate  and  bot.,  J  Ib 08 

Filter-paper,  gray,  25  sheets,  12x17 18 

Filter-paper,  white,  11  cm.  diam 13 

*  Gasoline. 

Grape-sugar,  commercial,  2  Ibs 19 

Hydrochloric  Acid  and  bot.,  6  Ibs « 85 

Iceland  Spar,  1  oz . 10 

Indigo,  1  oz 07 

Iodine  and  bot.,  f  oz 20 

Iron,  reduced  by  hydrogen,  J  Ib 45 

Iron,  filings,  1  Ib 05 

*  Kerosene. 

Lead  foil,  J  Ib 10 

Lead  Acetate  and  bot.,  2  oz  , 20 


130  APPENDIX. 

Lead  Nitrate  and  bot.,  2  oz $0.20 

Lead  Oxide,  litharge,  and  bot.,  J  Ib 15 

Lead  Oxide,  minium,  and  bot.,  J  Ib 18 

*  Lime. 

Lithium  Chloride  and  bot.,  -J  oz 15 

Litmus  Paper,  red  and  blue,  large  sheet,  each ...     .06 

Magnesium  ribbon,  5  ft 10 

Magnesium  Sulphate,  J  Ib 05 

Magnesium  Oxide  and  bot.,  J  Ib . . , 40 

Manganese  Dioxide,  1  Ib 06 

Manganous  Sulphate  and  bot.,  J  Ib 20 

*  Marble  or  limestone. 

Mercury  and  bot.,  J  Ib 24 

Mercuric  Chloride  and  bot.,  2  oz 20 

Mercuric  Oxide  and  bot.,  2  oz 30 

Methyl  Alcohol  and  bot,  J  Ib 10 

Nickel  Sulphate,  J  Ib 17 

Nitric  Acid  and  bot.,  7  Ibs 1.02 

Oxalic  Acid,  1  Ib 13 

Paraffine,  2  oz 05 

Phosphorus,  yellow,  and  bot.  and  can,  2  oz 38 

Phosphorus,  red,  and  bot.,  2  oz . . . 45 

Phosphoric  Acid,  ortho,  and  bot.,  2  oz ..........     .10 

Potassium,  metal,  and  bot.  and  can,  1  oz 1.70 

Potassium  Carbonate,  dry,  and  bot.,  2  oz 06 

Potassium  Bichromate,  \  Ib 09 

Potassium  Bromide,  \  Ib 18 

Potassium  Chromate,  J  Ib 15 

Potassium  Hydrate,  sticks,  pure  by  alcohol,  1  Ib., 

and  bot , 53 

Potassium  Ferrocyanide  and  bot.,  1  oz .08 

Potassium  Ferricyanide  and  bot.,  1  oz 10 

Potassium  Iodide  and  bot.,  J  Ib 74 

Potassium  Permanganate,  J  Ib 19 


APPENDIX.  131 

Kochelle  Salt,  J  Ib $0.09 

*  Salt. 

*  Soap. 

Silver  Nitrate  and  bot.,  1  oz 50 

Sodium,  metallic,  and  container,  1  oz 35 

Sodium  Bicarbonate,  J  Ib 05 

Sodium  Carbonate,  dry  powdered,  J  Ib 05 

Sodium  Carbonate,  crystals,  J  Ib 05 

Sodium  Hydrate,  sticks,  pure  by  alcohol,  1  Ib.,  and 

bot 50 

Sodium  Nitrate,  coral.,  1  Ib 11 

Sodium  Phosphate  (di),  J  Ib 10 

Sodium  Silicate,  water-glass,  £  Ib.,  and  bot 10 

Sodium  Sulphate,  ^  Ib , .     .05 

Sodium  Sulphide  and  bot.,  1  oz 08 

*  Starch. 

Strontium  Chloride,  J  Ib « t 10 

*  Sugar. 

Sulphur,  flowers,  1  Ib 05 

Sulphur,  roll,  1  Ib , 05 

Sulphuric  Acid,  c.  p.,  and  bot.,  9  Ibs 1.15 

Tartaric  Acid,  \  Ib 23 

Tartar  Emetic  and  bot.,  1  oz 08 

Tin,  granulated,  2  oz , 06 

*  Turpentine. 

Toluidine  (para),  crystals,  and  bot.,  1  oz 32 

*  Yeast. 

Zinc,  granulated,  2  Ibs 70 

Zinc  Oxide,  by  wet  process,  2  oz 10 

Except  when  specified  chemicals  are  put  up  in  paste- 
board boxes.  Bottles  are  furnished  for  all  chemicals 
at  $2.00  extra. 

The  plan  shown  in  Figs.  25  and  26  represents  a 


132 


APPENDIX. 


Floor  Pl< 


32.X3Q- 


Lecture  tabl« 


:1 


n 


FIG.  25. 


APPENDIX. 


133 


134  APPENDIX. 

room  22'  X  30'  fitted  with  two  work-tables  18'  long, 
38"  high,  and  30"  wide.  The  lecture-table  is  14'  long, 
33"  high,  36"  wide.  The  two  cases  for  books,  chemi- 
cals, and  apparatus  are  5'  long,  6^'  high,  and  18"  deep, 
with  about  four  shelves  to  each  case,  glass  doors  in 
front.  The  sink  should  be  of  enamelled  iron  or  slate, 
preferably  the  latter,  though  costing  somewhat  more, 
size  about  18"  X  40",  fastened  to  iron  brackets  on 
wall  or  cased  up  below  with  wood.  The  following 
material  may  be  used  for  construction  of  cases,  tables, 
etc. :  For  framing  2"  X  4"  scantling ;  doors  in  work- 
tables  and  panels  in  lecture-tables  f"  yellow-pine 
ceiling ;  drawer-fronts,  shelving,  cases,  casing,  etc.,  |" 
soft  pine ;  tops  of  work  and  lecture  tables  1J"  soft 
pine. 

A  laboratory  fitted  as  above  described  will  cost  from 
$125.00  to  $130.00,  including  varnish,  etc. 

The  central  part  of  the  room  has  ample  capacity  for 
seating. 


UNIVERSITY  OF  CALIFORNIA 


boo  7 


